Degradation of some biorecalcitrant pesticides by
CFS_预处理对不同秸秆原料酶解和理化结构的影响
山西农业科学 2023，51（12）：1426-1434Journal of Shanxi Agricultural SciencesCFS 预处理对不同秸秆原料酶解和理化结构的影响田鑫，王雨萌，徐师苗，汪强杰，胡轲，张海波，程红艳（山西农业大学 资源环境学院，山西 太谷 030801）摘要：高铁酸钾复合液（CFS ）是制备高铁酸钾的剩余滤液，其含有大量碱（OH -）和氧化剂（ClO -和Fe 6+），具有破坏木质纤维素顽固结构、提升酶解效率的潜力。
为实现秸秆的资源化利用与高铁酸钾制备废液的再利用，以山西储量丰富的玉米秸秆（CS ）、高粱秸秆（SS ）和谷子秸秆（MS ）为原料，采用CFS 进行预处理，对比3种秸秆的酶解糖化率，分析秸秆的理化结构变化。
结果表明，CFS 预处理中碱和氧化剂共同参与了3种秸秆的降解，促进了酶解糖化率；在最佳预处理时间24 h 下，CS 、SS 和MS 的还原糖产量分别较对照提高252.77%、236.39%、216.66%，其中CS 的酶解效率最高；组分分析表明，CFS 处理能有效去除3种秸秆中木质素成分，增加纤维素相对含量，进而有利于纤维素酶的可及性；结构分析显示，CFS 处理后，3种秸秆的理化结构发生了不同程度变化，粗糙度增加，官能团发生断裂，纤维结晶度升高，热稳定性变差。
在3种秸秆中，CS 结构变化最明显，更有利于被生物转化。
综上，CFS 预处理可改变作物秸秆的理化结构，破坏其致密结构，促进后续酶解效率，是一种理想的预处理技术。
关键词：高铁酸钾复合液（CFS ）；预处理；作物秸秆；还原糖产量；理化结构中图分类号：S141.4 文献标识码：A 文章编号：1002‒2481（2023）12‒1426‒09Effects of CFS Pretreatment on Enzymatic Hydrolysis and PhysicochemicalStructure of Different Straw MaterialsTIAN Xin ，WANG Yumeng ，XU Shimiao ，WANG Qiangjie ，HU Ke ，ZHANG Haibo ，CHENG Hongyan（College of Resources and Environment ，Shanxi Agricultural University ，Taigu 030801，China ）Abstract ： Composite ferrate solution(CFS) is the residual filtrate for preparing potassium ferrate. It contains a lot of alkali (OH -) and oxidant(ClO - and Fe 6+), which has the potential to destroy the recalcitrant structure of lignocellulose and improve the efficiency of enzymatic hydrolysis. In order to realize the utilization of straw resources and reuse of preparation waste liquid of potassium ferrate, in this paper, corn straw(CS), sorghum straw(SS), and millet straw(MS), which are abundant in Shanxi province, were pretreated with CFS, the enzymolysis and saccharification rates of the three kinds of straw were compared, and the change of physicochemical structure of the straw was analyzed. The results showed that the alkali and oxidant in the pretreatment of CFS were involved in the degradation of three kinds of straw, which promoted the enzymatic hydrolysis rate and saccharification rate. Under the optimal pretreatment time of 24 h, the reducing sugar yield of CS, SS, and MS was increased by 252.77%, 236.39%, and 216.66% compared with that of the control, respectively, and the enzymatic hydrolysis efficiency of CS was the highest. Component analysis showed that CFS treatment could effectively remove lignin in three kinds of straw and increase the relative content of cellulose, which was beneficial to the accessibility of cellulase. Structural analysis showed that after CFS treatment, the physicochemical structure of the three kinds of straw changed in different degrees, roughness increased, functional group fractured, fiber crystallinity increased, and thermal stability decreased. Among the three kinds of straw, CS had the most obvious structural change and was more conducive to biotransformation. In conclusion, CFS pretreatment could change the physicochemical structure of crop straws, destroy the dense structure and promote the efficiency of subsequent enzymatic hydrolysis, so it was an ideal pretreatment technology.Key words ：composite ferrate solution(CFS); pretreatment; crop straw; reducing sugar yield; physicochemical structuredoidoi:10.3969/j.issn.1002-2481.2023.12.11收稿日期：2023-01-04基金项目：山西省高等学校科技创新项目（2020L0137）；山西农业大学科技创新基金项目 （2018YJ39）；山西省优秀博士来晋工作奖励基金（SXYBKY201803）；国家自然科学基金（52100149）；山西省水利科学技术研究与推广项目（2022GM034）作者简介：田 鑫（1997-），女，山西汾阳人，在读硕士，研究方向：农业环境保护与废弃物资源化利用。
2024福建省中考英语作文
In the year2024,the Fujian Province middle school English composition exam may cover a wide range of topics that reflect the interests,concerns,and aspirations of students in that region.Here are some potential essay prompts that could be included in the exam,along with sample outlines and ideas for each:1.The Role of Technology in EducationIntroduction:Briefly introduce the significance of technology in modern education. Body Paragraph1:Discuss how technology enhances learning experiences through interactive tools and resources.Body Paragraph2:Explore the challenges technology brings,such as digital divide and overreliance on devices.Conclusion:Summarize the benefits and suggest a balanced approach to integrating technology in education.2.Cultural Heritage and Modern LifeIntroduction:Explain the importance of preserving cultural heritage.Body Paragraph1:Describe how cultural heritage enriches our lives and identities. Body Paragraph2:Discuss the impact of modernization on traditional cultures and the need for adaptation.Conclusion:Emphasize the importance of finding a balance between preserving heritage and embracing modernity.3.The Impact of Social MediaIntroduction:Present the pervasive influence of social media in todays society. Body Paragraph1:Highlight the positive aspects of social media,such as connectivity and information sharing.Body Paragraph2:Address the negative effects,including cyberbullying and privacy concerns.Conclusion:Offer suggestions for responsible social media use.4.The Importance of Environmental ProtectionIntroduction:State the urgency of environmental protection.Body Paragraph1:Discuss the consequences of environmental degradation,such as climate change and loss of biodiversity.Body Paragraph2:Suggest practical actions individuals and communities can take to protect the environment.Conclusion:Call for collective efforts to safeguard our planet for future generations.5.The Value of VolunteeringIntroduction:Introduce the concept of volunteering and its benefits.Body Paragraph1:Elaborate on how volunteering contributes to personal growth and community development.Body Paragraph2:Share personal experiences or stories of volunteers making a difference.Conclusion:Encourage more students to participate in volunteering activities.6.The Challenges of Balancing School and LeisureIntroduction:Discuss the importance of a balanced life for students.Body Paragraph1:Describe the pressures students face to perform academically. Body Paragraph2:Suggest ways to manage time effectively and incorporate leisure activities.Conclusion:Stress the importance of a wellrounded lifestyle for overall wellbeing.7.The Influence of GlobalizationIntroduction:Define globalization and its reach in the modern world.Body Paragraph1:Explore the economic and cultural benefits of globalization. Body Paragraph2:Discuss the potential drawbacks,such as cultural homogenization and economic disparities.Conclusion:Reflect on how to navigate the complexities of globalization.8.The Significance of Physical FitnessIntroduction:Emphasize the role of physical fitness in maintaining a healthy lifestyle. Body Paragraph1:Discuss the health benefits of regular exercise.Body Paragraph2:Address common barriers to physical activity and suggest solutions. Conclusion:Encourage students to prioritize physical fitness as part of their daily routine.9.The Power of PerseveranceIntroduction:Introduce the concept of perseverance and its significance in achieving goals.Body Paragraph1:Provide examples of individuals who have succeeded through perseverance.Body Paragraph2:Discuss strategies for developing a resilient mindset. Conclusion:Inspire students to embrace challenges and persist in the face of adversity.10.The Joy of ReadingIntroduction:Express the joy and enrichment that reading brings to ones life.Body Paragraph1:Discuss the cognitive and emotional benefits of reading.Body Paragraph2:Share personal favorite books or genres and their impact. Conclusion:Advocate for a culture of reading and lifelong learning.These prompts are designed to encourage students to think critically,express their opinions,and demonstrate their English writing skills.The essays should be wellorganized,with a clear introduction,body paragraphs that develop the ideas,and a conclusion that summarizes the main points.。
环评术语词汇大全
A名词转换：按比例采样proportional sampling从流动水中采样的技木。
在不连续采样时，其采祥次数或连续采样的流速与所采水的流速成正比。
名词转换：a系数alpha factor在活性污泥污水处理设备中，混合液与清洁水中氧传递系数之比。
名词转换：氨的气提ammoniastripping通过碱化和通气去除水中氨化合物的一种方法。
名词转换：岸滤bank filtration为了改善水质，引导河水透过岸边砂砾层而进行的过滤（集水并中把水抽到砂砾层，形成水力梯度）名词转换：氨化作用ammonification细菌转化含氮化合物为铵离子的过程B名词转换：β系数beta factor在活性污泥污水处理设备中，混合液中溶解氧饱和值与同一温度和气压下清洁水中溶解氧饱和值之比。
名词转换：半致死浓度（LC50）lethal concentration（LC50）在一特定接触时间内，使受试生物半数致死的毒物浓度。
通常是连续接触毒物，以LC50表示。
名词转换：半静态毒性试验semi-static toxicity test（定期更换受试液的毒性试验toxicity test with intermittent renewal）按比较长的间隔时间（如12或24小时）分批更换大部分（大于95％）试液；或定期（一般每隔24小时）将生物转移到与该毒物试验开始时相同浓度新配制的试液中。
名词转换：保守性物质conservative substance （持久性物质persistent substance；难分解物质质recalcitrant substance；难分解物质质recalcitrant substance；难处理物refractory substance）自然过程中化学组分不变化，或者变化极缓慢的物质。
例如；在污水处理过程中不能生物降解酶物质。
名词转换：病原体pathogen能够在易感染的植物、动物（包括人）体内引起疾病的生物。
Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acineto
Journal of Environmental Science and Engineering A 8 (2019) 131-140 doi:10.17265/2162-5298/2019.04.001D DAVID PUBLISHINGCrude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter johnsonii Firstly Isolated from Marine Sediments of Oran Port, AlgeriaFaiza Bendadeche1, Mohamed Bey Baba Hamed2 and Sidi-Mohammed El-Amine Abi Ayad11. Laboratory of Aquaculture and Bioremediation (AquaBior), Department of Biotechnology, Faculty of Nature and Life Sciences, University of Oran 1 Ahmed Ben Bella, Oran 31000, Algeria 2. Higher School of Biological Sciences of Oran, Oran 31000, AlgeriaAbstract: Petroleum contaminants caused great damages to environment and human health. Among, the port of Oran is subject of pollution mainly by PAHs (Polycyclic Aromatic Hydrocarbons) as a result of the large flow of ships. Thus bioremediation by indigenous microorganisms is an important means for their reduction and elimination. In the present work, a hydrocarbonoclastic bacterium strain SP49F2 was considered, firstly isolated from the contaminated marine sediments and seawater at the port of Oran (Algeria), using Bushnell-Hass mineral salt medium, and identified on the basis of morphological and biochemical characteristics and molecular tools by analysis of partial 16S rRNA gene sequence, using the Basic Local Alignment Search Tool program on the data base of NCBI (National Centre for Biotechnology Information), and the EzBioCloud 16S rRNA database. Kinetic of growth of this isolate on crude oil during 20 days of culture was studied at temperature 25 °C, 3% (w/v) of NaCl concentration and pH 7, at 140 rpm (Revolutions Per Minute). Strain SP49F2 was identified molecularly as Acinetobacter johnsonii, and might support high concentrations of crude oil (up to 10%, v/v). Results of growth kinetic on crude oil as sole energy and carbon source by the isolate strain showed that the stationary phase was attained at day 12. Thus, train Acinetobacter johnsonii SP49F2 could efficiently utilize crude oil as its sole carbon and energy source, and could be used as a wonderful native biological alternative for the bioremediation of the port of Oran, and marine area polluted by petroleum hydrocarbons, as an eco-friendly efficacy degrader, and may be suitable for biotechnological applications.Key words: Crude oil, Acinetobacter johnsonii, bioremediation, marine sediments, 16S rDNA.1. IntroductionAmong the environmental pollutants, the PAHs (Polycyclic Aromatic Hydrocarbons) are the most common, presenting mutagenic, toxic and carcinogenic properties [1]. When compared to the other chemicals of ecological concern, petroleum products such as gasoline, diesel, or lubricants are widely used. However, through oil spills accidents, and leaks during fuel production, exploration, transport, and storage, petroleum-based products areCorresponding author: Faiza Bendadeche, Ph.D., main research field: biotechnology and bioremediation.scattered into the environment [2]. Petroleum hydrocarbons present serious risks to thehealth of all living organisms in the world. For the remediation and management of petroleum hydrocarbons, various methods such as chemical, physical, and biological are presently usable. Between these methods, bioremediation is considered as an interesting substitution for removing petroleum hydrocarbons from contaminated areas, as an economical, cost-effective and eco-friendly method [2, 3].There are hundreds of species of fungi, archaea and bacteria that can degrade oil. Hydrocarbon-degrading132 Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter johnsonii Firstly Isolated from Marine Sediments of Oran Port, Algeriamicroorganisms are ubiquitous, but represent only a small part of the microbial communities [4]. It has been confirmed that the application of microorganisms is more appropriate, provides practical means for cleaning-up of contamination by petroleum hydrocarbons from harbors and marine environments, especially by indigenous microorganisms [5, 6]. In addition, native hydrocarbons-degrading bacteria proliferating in contaminated area as marine sediments are better adapted and more suitable for restoring the hydrocarbon contamination in sea [6, 7].The aim of the present work is to isolate indigenous hydrocarbon-degrading bacterial strains from contaminated marine sediments and seawater of the port of Oran (Algerian coast), with the capability to utilize crude oil, and to study the firstly isolated bacterial strain SP49F2, with its outstanding growth rate on crude oil as carbon and energy source.2. Material and Methods2.1 Sampling Site Localization and Samples CollectionMixed seawater and marine sediment samples of few millimeter of sediments surface were collected, in October 2013, from -40 m depth at port of Oran (Algerian coast) (latitude: 35°42′44″ N; longitude: 0°38′28″ W), and transported immediately to the Aquaculture and Bioremediation laboratory (AquaBior).2.2 Procedure of Enrichment, Isolation and Selection of Hydrocrbonoclastics BacteriaFor the isolation of hydrocarbon-degrading bacteria a synthetic BHMS (Bushnnell-Haas Mineral Salt) medium was used [8]. Sterilization of the BHMS medium was performed by autoclaving at 121 °C for 20 min, after adjusting pH at 7.2. Then, sterile crude oil (from the Hassi-Messaoud oil Refinery, Algeria) was added to cool BHMS medium as sole source of carbon and energy. Sterilization of crude oil was carried out using 0.22 µm filter membrane.To enrich culture, 2 mL of mixed seawater and marine sediments (from 40 m depth), after decantation, was taken and added to 100 mL BHMS, with 2% (v/v) of crude oil, in 500 mL Erlenmeyer flask, and incubated at 25 °C and 140 rpm (Revolutions Per Minute) in a shaker incubator (Heidolph Inkubator 1000 coupled with Heidolph Unimax 1010, Germany), for 7 days. For subsequent subculture, 1 mL of product of the enrichment culture was inoculated in fresh BHMS medium, then from the product of this last subculture, 1 mL was transferred to a series of four supplementary serial subcultures successively with 4%, 6%, 8% then 10% of crude oil (v/v) as sole carbon and energy source on BHMS medium. Every subculture was incubated for 72 h at 25 °C and 140 rpm. From the product of the last subculture flask, of 10% (v/v) of crude oil, inoculums were streaked out into BHMS agar medium plate, with addition of 10% (v/v) of crude oil, and incubated for 7 days at 25 °C. Purification of different colonies phenotypically was carried out in nutrient agar medium. Morphologically distinct pure cultures with higher visible growth rate and crude oil degradation on BHSM medium supplemented with 10% (v/v) of crude oil were selected, and stored at -20 °C until use.2.3 Physiological and Biochemical CharacteristicsThe physiological and biochemical typical characteristics of strain SP49F2, such as Gram staining, the oxidase activity (established by kit oxidase test (Sigma-Aldrich, Germany)), respiratory type (meat-liver agar), motility (Mannitol mobility medium), the catalase activity (defined by bubble formation in a 3% (w/v) solution of hydrogen peroxide), citrate utilization test (Simmons’ Citrate agar), TSI (Triple-Sugar-Iron) test, and the ability to growth in Chapman agar medium, Schubert medium, SS (Salmonella-Shigella) agar medium and BCPL (Brain-Heart Infusion Broth), were systematically analyzed according to Holt, et al. [9]. All biochemical tests above were carried out in triplicate.Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter 133 johnsonii Firstly Isolated from Marine Sediments of Oran Port, Algeria2.4 Molecular Identificationnumber MK334629.2.4.1 DNA ExtractionFrom grown cells, genomic DNA of strain SP49F2was extracted using an EasyPure® Bacteria GenomicDNA Kit (TransBionovo Co., Ltd., China), accordingto the manufacturer’s instructions. The extracted DNAwas stored at -20 °C until analysis.2.4.2 16S rRNA Gene Sequencing andPhylogenetic AnalysesPCR (Polymerase Chain Reaction) amplification ofthe 16S rRNA gene was conducted using DNAtemplate sample with the universal primers, forwardprimer ben27F (5’-AGAGTTTGATCCTGGCTC-3’)andreverseprimerben1492R(5’-GGTTACCTTGTTACGCTT-3’), synthesized bySigma (Germany). The PCR reaction mixture, with atotal volume of 50 μL, contained the following: 1 µLof DNA template (40 ng), 1 µL of ben27F (25 µM), 1µL of ben1492R (25 µM), 2.0 µL of dNTP (2.5 mM),2.0 µL of MgCL2 (50 mM), 5 µL of 10× buffer solution (20 mM), 0.5 µL of taq DNA polymerase (5 UL-1), and ddH2O. The PCR programmer was: 95 °C for 5 min; 35 cycles, 94 °C for 1 min denaturation,55 °C for 1 min annealing and 72 °C for 2 minextension; and final extension at 72 °C for 10 min.PCR products were analyzed by electrophoresis on 1.5%agarose gel and then partially sequenced by Genewiz.Sequence similarity was sought utilizing thealignment method and on the EzBioCloud 16S rRNAdatabase [10], using reference sequences, and theNCBI (National Centre for Biotechnology Information)database, using published 16s rDNA sequences. Dataanalysis of the partial 16S rDNA gene sequence wasperformed using MEGA (Molecular EvolutionaryGenetics Analysis) software package Version 7.0 [11],and using neighbor-joining methods the phylogenetictree was carried out.2.4.3 Nucleotide Sequence SubmissionThe partial 16S rDNA gene sequence of thehydrocarbonoclastic bacteria strain SP49F2 wassubmitted to the NCBI-GeneBank under the accession2.5 Kinetic of Growth on Crude Oil at Optimal Culture Conditions of the Isolate BacteriaThe strain SP49F2 was grown on BHMS medium with 2% of crude oil (v/v) as sole source of carbon and energy, under optimal cultivation conditions (studied previously), such as 3% (w/v) of NaCl, pH 7 and temperature 25 °C for about 20 days on an orbital shaker at 140 rpm (Heidolph Inkubator 1000 coupled with Heidolph Unimax 1010, Germany). Cultures were carried out in 250 mL flasks containing 50 mL of BHSM medium (Fig. 4), in triplicate. The growth rate of the isolate strain was estimated indirectly by measuring the OD (Optical Density 600 nm) with spectrophotometer (Perkin Elmer Lambda 35 UV/Vis Spectrometer, USA).3. Results3.1 Isolation of Hydrocarbonoclastic BacteriaHydrocarbonoclastic strains were enriched and separated by culturing contaminated seawater and marine sediment sampled from the port of Oran, Algeria, using enrichment cultures and dilution subcultures with increasing concentrations of crude oil (2%-10%, v/v). These isolates showed variable growth rates on the BHMS medium, supplemented with 2%-10% (v/v) of crude oil as the sole carbon and energy source (data not shown). Amongst, strain SP49F2 possessed remarkable growth rate, and efficiency of crude oil utilization, as sole carbon and energy source, and could support high concentrations of crude oil (up to 10%, v/v).3.2 Identification of Stain SP49F2Phylogenetic relationships between strain SP49F2 and other representative strains of the genus Acinetobacter were established. For that, about 1,500 pb of the 16S rDNA gene were amplified using universal primers by PCR (Fig. 1), then partial fragment of 987 pb from this gene was sequenced (GenBank ID:134 Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter johnsonii Firstly Isolated from Marine Sediments of Oran Port, AlgeriaPb5000 3000 2000 1500 1000 800500 300M12Fig. 1 Electrophoretis of the 16S rDNA gene PCR product of the bacterial strain SP49F2 on 1.5% agarose. Lanes 1 and 2: 16S rDNA; M: Trans5K DNA Marker.MK334629). This continuous sequence was analyzed using the Basic Local Alignment Search Tool program (/blast) by the GenBank database on the NCBI and the EzBioCloud database in EzTaxon. Sequence similarity calculation using alignment by BLAST on NCBI database revealed that the partial 16S rDNA gene sequence of the isolate strain SP49F2 belonged to Acinetobacter genus, with a high sequence similarity, of 100% with Acinetobacter johnsonii XBB1 (CP010350.1), and 100% with Acinetobacter johnsonii strain ATCC 17909 (NR_117624.1), and using alignment by EzBioCloud sequences, it had 99.90% of similarity with Acinetobacter johnsonii CIP 64.6 (APON01000005). Afterward, two phylogenetic trees were carried out using similar 16S rDNA sequences (Figs. 2a and 2b), using the Neighbor-Joining Method, based on the two programmes of alignement (EzBioCloud and NCBI databases).The phylogenetic trees indicated that the bacterial strain SP49F2 was related to species Acinetobacter johnsonii (Figs. 2a and 2b). For that, the strain SP49F2 was identified as Acinetobacter johnsonii.The isolate strain SP49F2 was found to be Gram negative, strict aerobic, motile, coccobacilli-shapedbacteria (Fig. 3a). The colonies on nutrient agar plate were whitish, smooth, circular, convex, opaque and > 0.5 mm in diameter after incubation for 24 h at 25 °C (Fig. 3b). Biochemical characteristics results of strain SP49F2 are regrouped in Table 1.3.3 Growths Kinetic of the Hydrocarbonoclastic of the Isolated Bacterial TrainThe bacterial stain SP49F2 was grown on BHMS medium, supplemented with 2% (v/v) of crude oil as sole carbon and energy source, during 20 days, on their optimal culture conditions (pH 7; temperature 25 °C and 3% (w/v) of NaCl concentration, studied previously). The growth rate of this bacterial isolate was measured at the optical density 600 nm, and the results are shown in Fig. 4. As shown in the curve, strain SP49F2 started the logarithmic growth phase from the first to 12th day, and then the stationary phase was attained at day 12.4. DiscussionThe strain SP49F2 was one of hydrocarbonoclastic bacterium memberships to Acinetobacter johnsonii, firstly isolated from marine sediment and seawater from the port Oran, Algeria, having potential to develop a method to bioremediate marine environments polluted by petroleum hydrocarbons.Partial sequence analysis of the 16S rDNA gene (978 bp) confirmed the identification as Acinetobacter johnsonii specie, with a similarity of 100% with Acinetobacter johnsonii XBB1 (CP010350.1), and 100% with Acinetobacter johnsonii strain ATCC 17909 (NR_117624.1), using BLAST alignment on NCBI database, and 99.90% of similarity with Acinetobacter johnsonii CIP 64.6 (APON01000005), using BLAST alignment on EzBioCloud database. In addition, the morphological characteristics of the strain SP49F2 were very similar to those of the Acinetobacter johnsonii reported previously. The results of the biochemical characteristics of the SP49F2 strain are shown in Table 1.Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter 135 johnsonii Firstly Isolated from Marine Sediments of Oran Port, AlgeriaAcinetobacter johnsonii strain LXL C1 (CP031011.1)Acinetobacter johnsonii strain IC001 (CP022298.1)Acinetobacter johnsonii strain M19 (CP037424.1) 86 Acinetobacter johnsonii strain DSM 6963 (NR_119114.1)Acinetobacter johnsonii strain ATCC 17909 (NR_117624.1)Strain SP49F2 Acinetobacter johnsonii XBB1 (CP010350.1)99 Acinetobacter haemolyticus strain ATCC 17906 (NR_117622.1) Acinetobacter haemolyticus strain DSM 6962 (NR_026207.1)Acinetobacter celticus strain ANC 3831 (NR_153741.1)77 87Acinetobacter albensis strain ANC 4874 (NR_145641.1)Acinetobacter proteolyticus strain NIPH 809 (NR_148846.1)Acinetobacter colistiniresistens strain NIPH 1859 (NR_157607.1)100 84 Acinetobacter gyllenbergii strain RUH 422 (NR_042026.1) Acinetobacter guillouiae strain ATCC 11171 (NR_117626.1)Acinetobacter bereziniae strain ATCC 17924 (NR_117625.1) Teredinibacter turnerae strain T7902 (NR_027564.1)Pseudomonas pachastrellae strain KMM 330 (NR_040991.1)99Pseudomonas syringae strain ICMP 3023 (NR_117820.1)0.0100(a)66 98Acinetobacter celticus strain ANC 4603 (MBDL01000001) Acinetobacter kyonggiensis strain ANC 5109 jgi (1102396)88Acinetobacte bohemicus strain ANC 3994 (KB849175)Acinetobacter johnsonii strain CIP 64.6 (APON01000005)98 Strain SP49F2Acinetobacter tjernbergiae strain DSM 14971 (ARFU01000016)55Acinetobacter beijerinckii strain CIP 110307 (APQL01000005)77 Acinetobacter haemolyticus strain CIP 64.3 (APQQ01000002)Acinetobacter colistiniresistens strain NIPH 2036 (KE340374)98 Acinetobacter proteolyticus strain NIPH 809 (KB849179) Acinetobacter gyllenbergii strain CIP 110306 (ATGG01000001)Acinetobacter guillouiae strain CIP 63.46 (APOS01000028)72 51Acinetobacter bereziniae strain LMG 1003 (AIEI01000248)Acinetobacter junii strain CIP 64.5 (APPX01000010)88Acinetobacter parvus strain DSM16617 (AIEB01000124)0.0020(b) Fig. 2 Phylogenetic trees of the 16S rDNA sequence of the SP49F2 strain and the closest-related species: (a) From the NCBI database; (b): From EzBioCloud database. The scale bar represents the sequence divergence. GenBank accession numbers are indicated in parenthesis. Calculations were carried out using the neighbor Neighbor-Joining method (bootstrap = 1,000) using the software MEGA 7.0.136 Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter johnsonii Firstly Isolated from Marine Sediments of Oran Port, AlgeriaTable 1 Morphological and biochemical characteristics of the isolated bacterial strain SP49F2.Characteristics Gram straining Shape Oxidase test Catalase test MotilityResults - (Fig. 3a) Coccobacilli (Fig. 3a) + +Mannitol Respiratory type TSI test H2S productionGas production Citrate utilization Chapman SS Lactose Glucose Saccharose IndoleNotes: “+”, positive reaction; “-”, negative reaction.Strict aerobic K/K -+ (Fig. 3d) -(a)(b)(c)(d)Fig. 3 Colonies growth and cells morphological aspects of the bacterial strain SP49F2 on different culture medium; (a):Gram negative bacterium of strain SP49F2 (10 × 100); (b): Colonies of the strain SP49F2 on the nutrient agar plate after 24 hof incubation; (c): Colonies of the strain SP49F2 on the Chapman medium agar plate after 24 h of incubation; on the right:Chapman medium agar without culture (control); (d): Growth of the strain SP49F2 on BHMS with 2% (v/v) of crude oil assole carbon and energy source after 7 days of incubation, on the left, BHMS with 2% (v/v) of crude oil without culture(control).OD at 600 nmCrude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter 137 johnsonii Firstly Isolated from Marine Sediments of Oran Port, Algeria0.5 0.450.4 0.350.3 0.250.2 0.150.1 0.050 0510152025Time (day)Fig. 4 Growth kinetic of the bacterial strain SP49F2 on 2% of crude oil (v/v) as sole source of carbon and energy at temperature 25 °C, pH 7 and 140 rpm over 20 days of incubation. Bars represent standard deviation and experiments were performed in triplicate.From results obtained from kinetic of biodegradation of crude oil by the isolated bacterial strain in Fig. 4, the stationary phase was attained at day 12. These results indicate that this bacterial strain SP49F2 had effectively the ability to degrade and use crude oil as the sole source of carbon and energy.Formerly, numerous strains of Acinetobacter sp. were informed to own their hydrocarbon-degrading aptitude [3, 12, 13]. Also, this species possessed the capability to remediate the hydrocarbon-contaminated environments [14]. Recent studies demonstrated production of biosurfactant by Acinetobacter sp. with potential application on hydrocarbon bioremediation [15, 16].Other studies showed the ability of strains of Acinetobacter sp. to the bioremediation of polluted environments by various compounds, such as pharmaceutic compounds, presenting ubiquitous pollutants, effecting aquatic organisms and human health, including SMX (Sulfamethoxazole), SD (Sulfadiazine), SMT (Sulfamethazine), THM (Trimethoprim), TCS (Triclosan), DFC (Diclofenac) and CBZ (Carbamazepine) [17]. Also, Acinetobacter sp. had capability to degrade herbicide used in agriculture, including FE (Fenoxaprop-P-Ethyl) [18],and DEHP (Di-2-Ethylhexyl Phthalate), one of PAEs(Phthalic Acid Esters), representing a group ofrefractory and hazardous compounds blended inplastics [19]. Bhattacharya and Gupta [20] and Pandaand Sarkar [21] demonstrated potential andapplication of Acinetobacter sp. in bioremediation anddetoxification of heavy-metals-rich industrialwastewater and in tannery effluents such as Cr (VI).Moreover, strains of Acinetobacter sp. were capableto use crude oil as a sole carbon and energy source [14,22, 23], and were described as the most dominantgenus in marine sediments [15].Strains of Acinetobacter johnsonii were capable ofbiodegradation of organophosphate pesticide, such asmalathion (O,O-dimethyl-S-[1,2-di(ethoxyl-carbonyl)ethyl] phosphoro-dithioate) used in agriculture [24],removal of inorganic impurity from waste oil andwash-down water [25], and biodegradation offungicide,suchascyprodinil(4-cyclopropyl-6-methyl-N-phenylpyrimidin-2-amine),used worldwide on agriculture as a broad-spectrumanilinopyrimidine, affecting the ecosystem, andcausing slight acute toxicity as well as groundwatercontamination [19, 26].In addition, Acinetobacter johnsonii could biodegrade138 Crude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter johnsonii Firstly Isolated from Marine Sediments of Oran Port, Algeriadiesel [12], and PAHs, such as pyrene, naphthalene, phenanthrene, and anthracene, and possessed catechol 2,3-dioxygenase enzyme exhibiting the higher capacity to degrade PAHs [27]. Xue, et al. [28] isolated bacterial from marine deep sea sediments and identified as Acinetobacter johnson.The isolate strain Acinetobacter johnsonii SP49F2 from contaminated marine sediments and sea water, in our study tolerates significant concentrations of crude oil (up to 10%, v/v), because of the polluted area and the induction of developed enzymes of interest. This tolerance may reflect the evolutionary adaptation that results in the high stability, allowing bacteria with the ability to react faster than bacteria without spoilage to new sources of hydrocarbons [29].Therefore, as an indigenous microorganism, Acinetobacter johnsonii SP49F2 is a very important and useful means for the bioremediation and decontamination of marine sediments such as the port of Oran.5. ConclusionIn the present paper, indigenous marine hydrocarbon-degrading bacterium strain SP49F2 was identified as Acinetobacter johnsonii, isolated from mixed seawater and marine sediment at the port of Oran (Algeria), according to phenotypic and phylogenetic characteristics, which is adapted to polluted environment and possessed high growth capacity in crude oil as sole carbon and energy source. Therefore, the isolate strain SP49F2 could be used as a convenient degrader, to initiate an advantageous eco-friendly method for the removal of hydrocarbon contaminations in different marine environments polluted by hydrocarbons, in especially, the port of Oran, Algeria.AcknowledgmentsThe authors thank scientific group of Aquaculture and Bioremediation Laboratory (AquaBior) for their fruitful help for the development of this work.References[1] Mnif, S., Chebbi, A., Mhiri, N., Sayadi, S., and Chamkha,M. 2017. “Biodegradation of Phenanthrene by a BacterialConsortium Enriched from Sercina Oil Field.” ProcessSaf Environ Prot 107: 44-53. doi:10.1016/j.psep.2017.01.023.[2] Logeshwaran, P., Megharaj, M., Chadalavada, S.,Bowman, M., and Naidu, R. 2018. “PetroleumHydrocarbons (PH) in Groundwater Aquifers: AnOverview of Environmental Fate, Toxicity, MicrobialDegradation and Risk-Based Remediation Approaches.”Environmental Technology & Innovation 10: 175-93. doi:10.1016/j.eti.2018.02.001.[3] Tiralerdpanich, P., Sonthiphand, P., Luepromchai, E.,Pinyakong, O., and Pokethitiyook, P. 2018. “PotentialMicrobial Consortium Involved in the Biodegradation ofDiesel, Hexadecane and Phenanthrene in MangroveSediment Explored by Metagenomics Analysis.” MarPollutBull133:595-605.doi:10.1016/j.marpolbul.2018.06.015.[4] Atlas, R. 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M., and Giuliano, L. 2007. “MicrobialCommunity Dynamics during Assay of Harbor Oil SpillBioremediation: A Microscale Simulation Study.” J. App.Microbiol.102:184-94.doi:10.1111/j.1365-2672.2006.03071.x.[8] Mehdi, H., and Giti, E. 2008. “Investigation of AlkaneBiodegradation Using the Microtiter Plate Method andCorrelation between Biofilm Formation, BiosurfactantProduction and Crude Oil Biodegradation.” IntBiodeterior Biodegradation 62: 170-8. doi:10.1016/j.ibiod.2008.01.004.[9] Holt, S. G., Kriey, N. R., Sneath, P. H. A., Staley, J. T.,and Williams, S. T., eds. 1998. Bergy’s Manual ofCrude Oil Degradation Potential of Indigenous Hydrocarbonoclastic Bacterial Strain Acinetobacter 139 johnsonii Firstly Isolated from Marine Sediments of Oran Port, AlgeriaDetermination for Bacteriology. New York: Williams andWilkins.[10] Yoon, S. H., Ha, S. M., Kwon, S., Lim, J., Kim, Y., Seo,H., and Chun, J. 2017. “Introducing EzBioCloud: ATaxonomically United Database of 16S rRNA GeneSequences and Whole-Genome Assemblies.”Int. J. Syst. Evol. Microbiol 67: 1613-7. doi:10.1099/ijsem.0.001755.[11] Kumar, S., Stecher, G., and Tamura, K. 2016. “MEGA7:Molecular Evolutionary Genetics Analysis Version 7.0for Bigger Datasets.” Mol. Biol. Evol. 33: 1870-4. doi:10.1093/molbev/msw054.[12] Lee, M., Woo, S.-G., and Ten, L. N. 2012.“Characterization of Novel Diesel-Degrading StrainsAcinetobacter haemolyticus MJ01 and Acinetobacterjohnsonii MJ4 Isolated from Oil-ContaminatedSoil.” World Journal of Microbiology andBiotechnology28(5):2057-67.doi:10.1007/s11274-012-1008-3.[13] Fang, Y., Zhang, L., Wang, J., Zhou, Y., and Ye, B. 2017.“Biodegradation of Phthalate Esters by a Newly IsolatedAcinetobacter sp. Strain LMB-5 and Characteristics of ItsEsterase.” Pedosphere 27 (3): 606-15. doi:10.1016/s1002-0160(17)60355-2.[14] Obafemi, Y. D., Taiwo, O. S., Omodara, O. J., Dahunsi,O. S., and Oranusi, S. 2018. “Biodegradation of CrudePetroleum by Bacterial Consortia from Oil-ContaminatedSoils in Ota, Ogun State, South-Western, Nigeria.”Environmental Technology & Innovation 12: 230-42. doi:10.1016/j.eti.2018.09.006.[15] Mahjoubi, M., Jaouani, A., Guesmi, A., Ben Amor, S.,Jouini, A., Cherif, H., et al. 2013. “HydrocarbonoclasticBacteria Isolated from Petroleum Contaminated Sites inTunisia: Isolation, Identification and Characterization ofthe Biotechnological.” New Biotechnol. 30 (6): 723-33.doi: 10.1016/j.nbt.2013.03.004.[16] Jadeja, N. B., Moharir, P., and Kapley, A. 2018.“Genome Sequencing and Analysis of Strains Bacillus sp.AKBS9 and Acinetobacter sp. AKBS16 for BiosurfactantProduction and Bioremediation.” Appl. Biochem.Biotechnol.187(20):518-30.doi:10.1007/s12010-018-2828-x.[17] Wang, W., Chen, X., Yan, H., Hu, J., and Liu, X. 2018.“Complete Genome Sequence of theCyprodinil-Degrading Bacterium Acinetobacter johnsoniiLXL_C1.” Microbial Pathogenesis 127: 246-9. doi:10.1016/j.micpath.2018.11.016.[18] Dong, W., Jiang, S., Shi, K., Wang, F., Li, S., Zhou, J., etal. 2015. “Biodegradation of Fenoxaprop-P-Ethyl (FE) byAcinetobacter sp. Strain DL-2 and Cloning of FEHydrolase Gene afeH.” Bioresource Technology 186:114-21. doi: 10.1016/j.biortech.2015.03.039.[19] Wang, J., Jiang, L.-H., Zhou, Y., and Ye, B.-C. 2017.“Enhanced Biodegradation of Di-n-butyl Phthalate byAcinetobacter Species Strain LMB-5 Coated withMagnetic Nanoparticles.” International Biodeterioration& Biodegradation 116: 184-90. doi:10.1016/j.ibiod.2016.10.024.[20] Bhattacharya, A., and Gupta, A. 2013. “Evaluation ofAcinetobacter sp. B9 for Cr (VI) Resistance andDetoxification with Potential Application inBioremediation of Heavy-Metals-Rich IndustrialWastewater.” Environmental Science and PollutionResearch20(9):6628-37.doi:10.1007/s11356-013-1728-4.[21] Panda, J., and Sarkar, P. 2011. “Bioremediation ofChromium by Novel Strains Enterobacter aerogenes T2and Acinetobacter sp. PD 12 S2.” Environmental Scienceand Pollution Research 19 (5): 1809-17. doi:10.1007/s11356-011-0702-2.[22] Hanson, K. G., Nigam, A., Kapadia, M., and Desai, A. J.1997. “News & Notes: Bioremediation of Crude OilContamination with Acinetobacter sp. A3.” CurrentMicrobiology35(3):191-3.doi:/10.1007/s002849900237.[23] Huang, H., Bowler, B. F. J., Oldenburg, T. B. P., andLarter, S. R. 2004. “The Effect of Biodegradation onPolycyclic Aromatic Hydrocarbons in Reservoired Oilsfrom the Liaohe Basin, NE China.” OrganicGeochemistry 35 (11-12): 1619-34. doi:10.1016/geochem.2004.05.009.[24] Xie, S., Liu, J., Li, L., and Qiao, C. 2009.“Biodegradation of Malathion by Acinetobacter johnsoniiMA19 and Optimization of Cometabolism Substrates.”Journal of Environmental Sciences 21 (1): 76-82. doi:10.1016/s1001-0742(09)60014-0.[25] Jiang, Y., Qi, H., Zhang, X., and Chen, G. 2012.“Inorganic Impurity Removal from Waste Oil andWash-Down Water by Acinetobacter johnsonii.” Journalof Hazardous Materials 239-240: 289-93. doi:10.1016/j.jhazmat.2012.08.076.[26] Chen, X., He, S., Liu, X., and Hu, J. 2018.“Biobegradation and Metabolic Mechanism of Cyprodinilby Strain Acinetobacter sp. from aContaminated-Agricultural Soil in China.” Ecotoxicologyand Environmental Safety 159: 190-7. doi:10.1016/j.ecoenv.2018.04.047.[27] Jiang, Y., Zhang, Z., and Zhang, X. 2018.“Co-biodegradation of Pyrene and Other PAHs by theBacterium Acinetobacter johnsonii.” Ecotoxicology andEnvironmental Safety 163: 465-70. doi:10.1016/j.ecoenv.2018.07.065.[28] Xue, D., Zeng, X., Lin, D., and Yao, S. 2018.“Thermostable Ethanol Tolerant Xylanase from a。
兰州大学生物学专业英语考试--- 词汇强化版之汉译英
(包围植物细胞液泡的)液泡膜tonoplast n.(跛子用的) 拐杖, 支撑, 帮助 crutch n.(产于非洲刚果河以南的)倭黑猩猩[源自非洲当地语]bonobo n.(法语中的) 英语外来语Franglais n.(俚语)脑袋 block n.(生) 进化枝,分化枝clade n.(生物)群体colony n.(时间) 短暂, (讲话, 文章等) 简短brevity n.(使)异化, (使)发生分解代谢catabolize v.(谈话, 写作等的) 题目, 主题 theme n.(学位)论文, 专题, 论述, 学术演讲dissertation n.(一种使用广泛的药物设计方法) 定量构效方法（quantitative structure-activity relationship ） QSAR n. (遗传)倒位 inversion n.(遗传)多倍体化 polyploidization n.[用作单或复](尤指生物体的) 形态测定,形态特征 morphometrics n.n. 启动子分析 promoter analysissmooth endoplasmic reticulum光滑内质网x-射线晶体学 x-ray crystallography n.X-射线衍射 X-ray diffraction阿尔茨海默病（即老年痴呆）Alzheimer's disease n.艾德曼降解法 Edman degradation n.把...作成公式, 用公式表示formulate vt.百科全书encyclopedia n.半科普的 semi-popular adj.胞嘧啶 cytosine n.比较的, 相当的 n.比较级comparative adj.编制目录 catalogue vt.扁囊，池，封闭的膜系统及其围成的腔构成网状膜结构cistena n.表达cDNA序列标签expressed cDNA sequence tag (EST) n.表面等离谐振。
保护环境英语作文
Protecting the environment is a responsibility that each of us should take seriously. Here are some key points to consider when writing an essay on this topic:1.Introduction to the Issue:Begin by introducing the importance of the environment and how it affects our daily lives.Mention the current environmental challenges such as pollution,deforestation,and climate change.2.Causes of Environmental Degradation:Discuss the various factors that contribute to environmental problems.This could include industrial activities,excessive use of fossil fuels,improper waste management,and overpopulation.3.Effects on Ecosystems and Human Health:Explain the consequences of environmental degradation on ecosystems,wildlife,and human health.Highlight issues such as loss of biodiversity,air and water pollution,and the spread of diseases.4.Individual Actions:Emphasize the role of individuals in protecting the environment. Suggest practical steps that can be taken,such as reducing waste,recycling,conserving water,and using public transportation.munity and Government Initiatives:Discuss the role of communities and governments in implementing policies and regulations to protect the environment. Mention the importance of environmental education and awareness campaigns.6.Technological Solutions:Explore how technology can help in environmental conservation,such as renewable energy sources,electric vehicles,and energyefficient appliances.7.International Cooperation:Stress the need for international cooperation in addressing global environmental issues.Discuss agreements like the Paris Agreement and the role of international organizations in promoting sustainable development.8.Conclusion:Summarize the main points and reiterate the importance of environmental protection.Encourage readers to take action and contribute to the preservation of our planet.9.Call to Action:End the essay with a call to action,urging readers to not only be aware of the environmental issues but also to actively participate in solving them.10.Personal Reflection:Optionally,include a personal reflection on how you have been affected by environmental issues or how you have contributed to environmentalconservation.Remember to use clear and concise language,provide evidence to support your arguments,and maintain a logical flow throughout the essay.。
表面活性剂对土壤中镉的吸附解析的研究
些为 １６ ｍｇ·Ｌ－１。ｐＨ 值对表面活性剂和土壤中的重金属镉去除也有影响， 当 ｐＨ 值为 ３ 时， 司班（ 山犁糖醇酐单月桂酸） 对
土壤中的重金属镉的去除效率还不明显， 而当 ｐＨ 值为 ４ 时， 司班对土壤中的重金属镉的去除有较好的效果。这说明 ｐＨ
值对表面活性剂和土壤中的重金属镉去除的影响非常敏感而且相当重要。
关键词： 土壤； 重金属； 表面活性剂； 吸附解析； 原子分光光度计
中图分类号： Ｘ５
文献标识码： Ａ
文章编号： １００４－ ８６４２（ ２００７） Ｓ２－ ０００４－ ０３
Ｓｔｕｄｙ ｏｎ Ｃａｄｍｉｕｍ Ａｂｓｏｒ ｐｔｉｏｎ－ ｅｘｔｒ ａｃｔｉｏｎ ｂｅｔｗｅｅｎ Ｓｕｒ ｆａｃｔａｎｔ ａｎｄ Ｓｏｉｌ ＨＵ Ｓｕｉ－ ｘｉ， Ｂａｙａｅｒ， ＺＨＡＮＧ Ｊｉａｎ－ ｐｉｎｇ， ＷＡＮＧ Ｌｉ－ ｂｉｎ， ＬＩＵ Ｌｉ－ ｘｉｎ
２ 结果与讨论
２．１ 结果 ２．１．１ 滤液中 Ｃｄ 吸光度的测定
用 ３１５０ 型原子吸收分光光度计在波长为 ２１７．６ ｎｍ 下用 Ｃｄ 阴极灯对 １．４ 节中的滤液（ １００ ｍＬ） 进行 测定， 每个样品测 ３ 个数据再取平均值。测定结果如 表 １ ～３：
表 １ 十二烷基苯磺酸钠作用下土壤溶液中 Ｃｄ２＋的吸光度
吸光度
Ｂ１ ０．１１９
Ｂ２ ０．１０４Ｂ５
Ｂ６
０．００７ ０．０１７
表 ２ 十二烷基硫酸钠作用下土壤溶液中 Ｃｄ２＋的吸光度
吸光度
Ｓ１ ０．１１８
Ｓ２ ０．０１６
Ｓ３ ０．００７
Ｓ４ ０．００５
Ｓ５ ０．００１
Ｓ６ ０．００８
表 ３ 司班作用下土壤溶液中 Ｃｄ２＋的吸光度
Effect of pyrolysis temperature and
holding time on biochar propertiesBiochar is becoming an increasingly popular alternative to traditional methods for managing soil organic matter, improving soil fertility, and sequestering carbon by converting agricultural wastes into a stable and recalcitrant form of carbon. Pyrolysis, the thermal decomposition of organic matter in the absence of oxygen, is widely used to produce biochar. The pyrolysis temperature and holding time are two critical factors that influence the properties of biochar. This article aims to explore the effect of pyrolysis temperature and holding time on biochar properties and their implications for soil management.Pyrolysis temperaturePyrolysis temperature is a important factor that influences the physicochemical properties of biochar. It determines the degree of thermal degradation of the material, leading to the production of different biochar properties. The effect of pyrolysis temperature on biochar properties can be divided into three categories: chemical composition, physical characteristics, and adsorption properties.Chemical compositionPyrolysis temperature has a significant effect on the chemical composition of biochar, including carbon content, ash content, pH, and functional groups. Higher pyrolysis temperatures generally result in higher carbon content, lower ash content, and higher pH. As the temperature increases, volatile components are driven off, leaving behind a more stable and recalcitrant carbon structure. At the same time, the increase in temperature may cause some functional groups, such as carboxyl and hydroxyl groups, to be decomposed, leading to a decrease in surface functional groups and a corresponding increase in hydrophobicity of the biochar.Physical characteristicsPyrolysis temperature also affects the physical characteristics of biochar, including surface area, pore size distribution, and bulk density. High-temperature pyrolysis leads to the formation of a more open pore structure and a higher surface area. However, pore size distribution is affected by both pyrolysis temperature and the type of feedstock, with higher temperatures resulting in a shift towards smaller pore sizes. Meanwhile, an increase in pyrolysis temperature may cause a decrease in bulk density and an increase in particle size.Adsorption propertiesPyrolysis temperature affects the adsorption properties of biochar, including its ability to adsorb nutrients, heavy metals, and other pollutants. High-temperature pyrolysis generally results in biochar with a higher adsorption capacity due to its higher surface area and pore volume. At the same time, the decrease in functional groups may lead to a reduction in the biochar’s ability to adsorb certain types ofpollutants. The specific effect of pyrolysis temperature on the adsorption properties of biochar is determined by the type and concentration of the adsorbate, as well as the properties of the biochar itself.Holding timeHolding time is another important parameter in pyrolysis that affects the properties of biochar. The holding time is the duration of the pyrolysis process at a given temperature. It is an important factor that determines the final carbonization degree and the degree of thermal degradability of the feedstock. The effects of holding time on biochar properties include chemical composition, surface area, and adsorption properties.Chemical compositionIncreasing the holding time can promote the decomposition of organic matter and improve the carbonization degree of the biochar. However, excessive holding time can lead to excessive thermal degradation and a reduction in the carbon content of the final biochar. The chemical composition of biochar can be affected by the holding time either directly or indirectly. Longer holding times can result in greater efforts to remove moisture and volatile organic matter components from the feedstock, leading to higher carbon yield and lower ash content.Surface areaHolding time can also affect the specific surface area of biochar. As the holding time increases, the surface area of the biochar may increase due to an increase in the extent of decomposition and subsequent micropore formation. However, too long a holding time can also lead to a reduction in specific surface area due to excessive carbonization and vaporization of the volatile components.Adsorption propertiesHolding time can also affect the adsorption performance of biochar. An increase in holding time can result in a higher surface area and micropore volume, leading to a greater adsorption capacity for certain types of pollutants such as heavy metals. However, excessive holding times can reduce the number of surface functional groups responsible for adsorption, merely increasing the micropore density in the biochar, and reducing the potential for adsorption of some other pollutants.ConclusionIn conclusion, pyrolysis temperature and holding time are two crucial factors that influence the properties of biochar, which in turn determine its effectiveness in soil applications. High-temperature pyrolysis tends to result in biochar with higher carbon content, larger surface area, and higher adsorption capacity than low-temperature pyrolysis. Longer holding times can also modify biochar properties,although the extent depends on the conditions of the individual pyrolysis process. A well-designed pyrolysis process can thus be tailored to produce biochar with specific properties suitable for a wide range of soil applications, such as improving soil fertility, reducing greenhouse gas emissions, and remediating contaminated soils.。
建议一种方法处理水污染的英语作文
建议一种方法处理水污染的英语作文Water, the essence of life, is facing an unprecedented crisis of pollution. The degradation of water quality, resulting from industrial discharges, agricultural runoff, and urban sewage, is a global challenge that demands urgent attention. To tackle this issue effectively, a comprehensive strategy is needed that encompasses various measures to protect and restore the purity of our water resources.Firstly, strict regulations must be implemented tolimit industrial pollution. Factories and manufacturing units should be required to adhere to stringent emission standards, ensuring that harmful chemicals and toxins are not released into water bodies. This can be achieved through the enforcement of pollution control laws and the imposition of hefty fines for violations.Secondly, agricultural practices need to be modified to reduce runoff pollution. The excessive use of fertilizers and pesticides in farming leads to soil and water contamination. To address this, farmers can be encouraged to adopt sustainable farming methods, such as crop rotationand organic farming, which reduce the need for harmful chemicals.Moreover, urban planning should prioritize water conservation and treatment facilities. Sewage treatment plants should be expanded and upgraded to efficiently process wastewater, removing contaminants before the water is released back into the environment. Additionally, rainwater harvesting and reuse systems can be implemented to conserve water and reduce the burden on existing water resources.Furthermore, public awareness and education are crucial in the fight against water pollution. People should be made aware of the importance of water conservation and the harmful effects of water pollution. Educational campaigns and community events can be organized to promote water-saving practices and encourage individuals to play their part in protecting water resources.Lastly, technological innovation holds the key to addressing water pollution effectively. Advanced water treatment technologies, such as reverse osmosis and nanofiltration, can remove even the most recalcitrantpollutants from water. Investments in research and development of these technologies should be increased to make them more accessible and affordable.In conclusion, addressing water pollution requires a holistic approach that encompasses regulatory enforcement, sustainable agricultural practices, urban planning, public awareness, and technological innovation. Only through a concerted effort from all stakeholders can we ensure the protection and restoration of our precious water resources, safeguarding the future of life on Earth.**处理水污染：一种多层面的策略**水，生命的源泉，正面临着前所未有的污染危机。
专业英语翻译
2. Of more resent introduction is mushroom cultivation which probably dates back many hundreds of years for Japanese shii-ta-ke cultivation and about 300 years for the Agaricus mushroom now widely cultivated throughout the temperate world.
译文：生物工程反应可以是分解代谢反应或合成代谢反应（也叫生物合成反应）。分解代谢反应中复杂的化合物被分解为简单物质（葡萄糖生成乙醇），而合成代谢反应或生物合成反应，是简单的分子合成为更复杂的物质（抗生素的合成）。
3.biotechnology includes fermentation process(ranging from beers and wines to bread, cheese, antibiotics and vaccines), water and waste treatment, parts of food technology, and an increasing range of novel applications(ranging from biomedical to metal recovery from low grade ores
译文: 生物工程是属于应用生物科学和技术的一个领域，它包含生物或其亚细胞组分在制造业、服务业和环境管理等方面的应用。
2.The reactions of biotechnological processes can be catabolic, in which complex compounds are broken down to simpler ones (glucose to ethanol ), or anabolic or biosynthetic, whereby simple molecules are built up into more complex ones(antibiotic synthesis).
Bacterial Communities in Bioreactors
Bacterial Communities in BioreactorsBacterial communities in bioreactors play a crucial role in various industrial processes, including wastewater treatment, biofuel production, and biopharmaceutical manufacturing. These communities are composed of diversebacterial species that work together to carry out specific functions, such as breaking down organic matter or producing valuable compounds. However, maintaining a stable and efficient bacterial community in bioreactors can be challenging, asit is influenced by various factors such as environmental conditions, nutrient availability, and competition among different bacterial species. One of the key challenges in managing bacterial communities in bioreactors is maintaining their stability and resilience in the face of environmental fluctuations. Bioreactorsare often subjected to changes in temperature, pH, and nutrient levels, which can disrupt the balance of the bacterial community and lead to decreased efficiency in the bioreactor's performance. For example, a sudden increase in temperature can favor the growth of certain bacterial species over others, leading to a shift in the community structure and potentially compromising the bioreactor's function. Therefore, it is important to design bioreactor systems that can provide a stable and consistent environment for the bacterial community to thrive. Another challenge in managing bacterial communities in bioreactors is understanding and controlling the interactions between different bacterial species. Bacterial communities are complex networks of interactions, including competition for resources, cooperation in metabolic processes, and antagonistic behaviors such as the production of antimicrobial compounds. These interactions can have asignificant impact on the overall performance of the bioreactor, as they can influence the metabolic pathways and growth rates of the bacterial species present. Therefore, it is essential to study the dynamics of these interactions and develop strategies to promote the growth of beneficial bacterial species while suppressing the growth of harmful ones. In addition to maintaining stability and managing interactions, another important aspect of managing bacterial communities in bioreactors is optimizing their performance for specific industrial applications. Different bioreactor systems are used for various purposes, such as wastewater treatment, biofuel production, and pharmaceutical manufacturing, each requiring aspecific set of bacterial species and metabolic activities. Therefore, it is essential to tailor the composition and function of the bacterial community to meet the requirements of the desired industrial process. This may involveselecting specific bacterial strains with desired traits, engineering their metabolic pathways, or optimizing the bioreactor's operating conditions to maximize the production of desired compounds. Despite the challenges involved in managing bacterial communities in bioreactors, significant progress has been made in recent years through the application of advanced technologies and interdisciplinary approaches. For example, the development of high-throughput sequencing techniques has allowed researchers to study the composition and dynamics of bacterial communities in bioreactors at an unprecedented level of detail. This has led to a better understanding of the factors that influence community stability and the interactions between different bacterial species, enabling the development of more targeted strategies for community management. Furthermore, the integration of computational modeling and simulation has allowed researchers to predict the behavior of bacterial communities in bioreactors under different conditions, facilitating the design of more robust and efficient bioreactor systems. Additionally, the use of synthetic biology approaches has enabled the engineering of bacterial species with specific functions, such as the production of high-value chemicals or the degradation of recalcitrant pollutants. These technological advancements have significantly advanced our ability to manage and manipulate bacterial communities in bioreactors, paving the way for the development of more sustainable and efficient industrial processes.。
超声增强的输送的物料进入并通过皮肤翻译
超声增强的输送的物料进入并通过皮肤翻译Ultrasound-enhanced delivery of materials into and through the skinA method for enhancing the permeability of the skin or other biological membrane to a material such as a drug is disclosed. In the method, the drug is delivered in conjunction with ultrasound having a frequency of above about 10 MHz. The method may also be used in conjunction with chemical permeation enhancers and/or with iontophoresis.图片(11)权利要求(21)We claim:1. A method for enhancing the rate of permeation of a drug medium into a selected intact area of an individual's body surface, which method comprises:(a) applying ultrasound having a frequency of above 10 MHz to said selected area, at an intensity and for a period of timeeffective to enhance the permeability of said selected area;(b) contacting the selected area with the drug medium; and(c) effecting passage of said drug medium into and through said selected area by means of iontophoresis.2. The method of claim 1, wherein said ultrasound frequency is in the range of about 15 MHz to 50 MHz.3. The method of claim 2, wherein said ultrasound frequency is in the range of about 15 to 25 MHz.4. The method of claim 1, wherein said period of time is in the range of about 5 to 45 minutes.5. The method of claim 4, wherein said period of time is in the range of about 5 to 30 minutes.6. The method of claim 1, wherein said period of time is less than about 10 minutes.7. The method of claim 1, wherein said intensity of said ultrasound is less than about 5.0W/cm.sup.2.8. The method of claim 7, wherein said intensity of said ultrasound is in the range of about 0.01 to 5.0 W/cm.sup.2.9. The method of claim 8, wherein said intensity of said ultrasound is in the range of about 0.05 to 3.0 W/cm.sup.2.10. The method of claim 1, wherein said area of the stratum corneum is in the range of about 1 to 100 cm.sup.2.11. The method of claim 10, wherein said area of the stratum corneum is in the range of about 5 to 100 cm.sup.2.12. The method of claim 11, wherein said area of the stratum corneum is in the range of about 10 to 50 cm.sup.2.13. The method of claim 1 wherein said drug medium comprises a drug and a coupling agent effective to transfer said ultrasound to the body from an ultrasound source.14. The method of claim 13 wherein said coupling agent is a polymer or a gel.15. The method of claim 13 wherein said coupling agent is selected from the group consisting of glycerin, water, and propylene glycol.16. The method of claim 1 wherein said drug medium further comprises a chemical permeation enhancer.17. The method of claim 1, wherein steps (a) and (b) are carried out approximately simultaneously.18. The method of claim 1, wherein step (b) is carried out before step (a).19. The method of claim 1, wherein step (a) is carried out before step (b).20. The method of claim 1, wherein the ultrasound is applied continuously.21. The method of claim 1, wherein the ultrasound is pulsed.说明This application is a division of application Ser. No. 07/844,732 filed Mar. 2, 1992, now U.S. Pat. No. 5,231,975 which is a divisional of application Ser. No. 07/484,560, now U.S. Pat. No. 5,115,805, filed Feb. 23, 1990.TECHNICAL FIELDThis invention relates generally to the field of drug delivery. More particularly, the invention relates to a method of enhancing the rate of permeation of topically, transmucosally or transdermally applied materials using high frequency ultrasound.BACKGROUNDThe delivery of drugs through the skin ("transdermal drug delivery" or "TDD") provides many advantages; primarily, such a means of delivery is a comfortable, convenient and non-invasiveway of administering drugs. The variable rates of absorption and metabolism encountered in oral treatment are avoided, and other inherent inconveniences--e.g., gastrointestinal irritation and the like--are eliminated as well. Transdermal drug delivery also makes possible a high degree of control over blood concentrations of any particular drug.Skin is a structurally complex, relatively impermeable membrane. Molecules moving from the environment into and through intact skin must first penetrate the stratum corneum and any material on its surface. They must then penetrate the viable epidermis, the papillary dermis, and the capillary walls into the blood stream or lymph channels. To be so absorbed, molecules must overcome a different resistance to penetration in each type of tissue. Transport across the skin membrane is thus a complex phenomenon. However, it is the stratum corneum, a layer approximately 5-15 micrometers thick over most of the body, which presents the primary barrier to absorption of topical compositions or transdermally administered drugs. It is believed to be the high degree of keratinization within its cells as well as their dense packing and cementation by ordered, semicrystalline lipids which create in many cases a substantially impermeable barrier to drug penetration. Applicability of transdermal drug delivery is thus presently limited, because the skin is such an excellent barrier to the ingress of topically applied materials. For example, many of the new peptides and proteins now produced as a result of the biotechnology revolution cannot be delivered across the skin in sufficient quantities due to their naturally low rates of skin permeability.Various methods have been used to increase skin permeability, and in particular to increase the permeability of thestratum corneum (i.e., so as to achieve enhanced penetration, through the skin, of the drug to be administered transdermally). The primary focus has been on the use of chemical enhancers, i.e., wherein drug is coadministered with a penetration enhancing agent (or "permeation enhancer"). While such compounds are effective in increasing the rate at which drug is delivered through the skin, there are drawbacks with many permeation enhancers which limit their use. For example, many permeation enhancers are associated with deleterious effects on the skin (e.g., irritation). In addition, control of drug delivery with chemical enhancement can be quite difficult.Iontophoresis has also been used to increase the permeability of skin to drugs, and involves (1) the application of an external electric field, and (2) topical delivery of an ionized form of drug (or of a neutral drug carried with the water flux associated with ion transport, i.e., via "electroosmosis"). While permeation enhancement via iontophoresis has, as with chemical enhancers, been effective, there are problems with control of drug delivery and the degree of irreversible skin damage induced by the transmembrane passage of current.The presently disclosed and claimed method involves the use of ultrasound to decrease the barrier function of the stratum corneum and thus increase the rate at which a drug may be delivered through the skin. "Ultrasound" is defined as mechanical pressure waves with frequencies above 20,000 Hz (see, e.g., H. Lutz et al., Manual of Ultrasound: 1. Basic Physical and Technical Principles (Berlin: Springer-Verlag, 1984)).As discussed by P. Tyle et al. in Pharmaceutical Research 6(5):355-361 (1989), drug penetration achieved via "sonophoresis" (the movement of drugs through skin under theinfluence of an ultrasonic perturbation; see D. M. Skauen and G. M. Zentner, Int. J. Pharmaceutics 20:235-245 (1984)), is believed to result from thermal, mechanical and chemical alteration of biological tissues by the applied ultrasonic waves. Unlike iontophoresis, the risk of skin damage appears to be low.Applications of ultrasound to drug delivery have been discussed in the literature. See, for example: P. Tyle et al., supra (which provides an overview of sonophoresis); S. Miyazaki et al., J. Pharm. Pharmacol. 40:716-717 (1988) (controlled release of insulin from a polymer implant using ultrasound); J. Kost et al., Proceed. Intern. Symp. Control. Rel. Bioact. Mater.16(141):294-295 (1989) (overview of the effect of ultrasound on the permeability of human skin and synthetic membranes); H. Benson et al., Physical Therapy 69(2):113-118 (1989) (effect of ultrasound on the percutaneous absorption of benzydamine); E. Novak, Arch. Phys. Medicine & Rehab. 45:231-232 (1964) (enhanced penetration of lidocaine through intact skin using ultrasound); J. E. Griffin et al., Amer. J. Phys. Medicine 44(1):20-25 (1965) (ultrasonic penetration of cortisol into pig tissue); J. E. Griffin et al., J. Amer. Phys. Therapy Assoc.46:18-26 (1966) (overview of the use of ultrasonic energy in drug therapy); J. E. Griffin et al., Phys. Therapy 47(7):594-601 (1967) (ultrasonic penetration of hydrocortisone); J. E. Griffin et al., Phys. Therapy 48(12):1336-1344 (1968) (ultrasonic penetration of cortisol into pig tissue); J. E. Griffin et al., Amer. J. Phys. Medicine 51(2):62-72 (1972) (same); J. C. McElnay, Int. J. Pharmaceutics 40:105-110 (1987) (the effect of ultrasound on the percutaneous absorption of fluocinolone acetonide); and C. Escoffier et al., Bioeng. Skin 2:87-94 (1986) (in vitro study of the velocity of ultrasound in skin).In addition to the aforementioned art, U.S. Pat. Nos. 4,767,402 and 4,780,212 to Kost et al. relate specifically to the use of specific frequencies of ultrasound to enhance the rate of permeation of a drug through human skin or through a synthetic membrane.While the application of ultrasound in conjunction with drug delivery is thus known, results have for the most part been disappointing, i.e., enhancement of skin permeability has been relatively low.SUMMARY OF THE INVENTIONThe present invention provides a novel method for enhancing the rate of permeation of a given material through a selected intact area of an individual's body surface. The method comprises contacting the selected intact area with the material and applying ultrasound to the contacted area. The ultrasound preferably has a frequency of above about 10 MHz, and is continued at an intensity and for a period of time sufficient to enhance the rate of permeation of the material into and through the body surface. The ultrasound can also be used to pretreat the selected area of the body surface in preparation for drug delivery, or for diagnostic purposes, i.e., to enable non-invasive sampling of physiologic material beneath the skin or body surface.In addition to enhancing the rate of permeation of a material, the present invention involves increasing the permeability of a biological membrane such as the stratum corneum by applying ultrasound having a frequency of above about 10 MHz to the membrane at an intensity and for a period of time sufficient to give rise to increased permeability of the membrane. Once the permeability of the membrane has been increased, it is possible to apply a material thereto and obtain an increased rate of flowof the material through the membrane.It is accordingly a primary object of the invention to address the aforementioned deficiencies of the prior art by providing a method of enhancing the permeability of biological membranes and thus allow for an increased rate of delivery of material therethrough.It is another object of the invention to provide such a method which is effective with or without chemical permeation enhancers.It is still another object of the invention to minimize lag time in such a method and provide a relatively short total treatment time.It is yet another object of the invention to provide such a method in which drug delivery is effected using ultrasound.It is a further object of the invention to enable sampling of tissue beneath the skin or other body surface by application of high frequency (>10 MHz) ultrasound thereto.A further feature of the invention is that it preferably involves ultrasound of a frequency greater than about 10 MHz.Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.BRIEF DESCRIPTION OF THE DRAWINGSFIGS. 1A, 1B and 1C are theoretical plots of energy dissipation within the skin barrier versus frequency of applied ultrasound.FIGS. 2, 3 and 4 are graphic representations of the amount of salicylic acid recovered from the stratum corneum after ultrasound treatment at different frequencies.FIGS. 5 and 6 represent the results of experiments similar to those summarized in FIGS. 2, 3 and 4, but with a shorter treatment time.FIGS. 7, 8, 9 and 10 are plots of enhancement versus "tape-strip number," as described in the Example.FIG. 11 illustrates the effect of ultrasound on the systemic availability of salicylic acid following topical application.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTSBefore the present method of enhancing the rate of permeation of a material through a biological membrane and enhancing the permeability of membranes using ultrasound are disclosed and described, it is to be understood that this invention is not limited to the particular process steps and materials disclosed herein as such process steps and materials may, of course, vary. It is alto to be understood that the terminology used herein is used for purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present invention will be limited only by the appended claims.It must be noted that as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to "a drug" includes mixtures of drugs and their pharmaceutically acceptable salts, reference to "an ultrasound device" includes one or more ultrasound devices of the type necessary for carrying out the present invention, and reference to "the method of administration" includes one or more different methods of administration known to those skilled in the art or which will become known to those skilled in the art upon reading this disclosure.In one aspect of the invention a method is provided forenhancing the permeation of a given material such as a drug, pharmacologically active agent, or diagnostic agent into and/or through a biological membrane on an individual's body surface, which method comprises: (a) contacting the membrane with the chosen material in a pharmacologically acceptable carrier medium; and (b) applying ultrasound of an intensity and for a treatment time effective to produce delivery of the material through the membrane. The material is preferably a drug and it is preferable to obtain a desired blood level of the drug in the individual. The ultrasound is of a frequency and intensity effective to increase the permeability of the selected area to the applied drug over that which would be obtained without ultrasound. The ultrasound preferably has a frequency of more than 10 MHz, and may be applied either continuously or pulsed, preferably continuously. The ultrasound may be applied to the skin either before or after application of the drug medium so long as administration of the ultrasound and the drug medium is relatively simultaneous, i.e., the ultrasound is applied within about 6, more preferably within about 4, most preferably within about 2 minutes of drug application.The invention is useful for achieving transdermal permeation of pharmacologically active agents which otherwise would be quite difficult to deliver through the skin or other body surface. For example, proteinaceous drugs and other high molecular weight pharmacologically active agents are ideal candidates for transdermal, transmucosal or topical delivery using the presently disclosed method. In an alternative embodiment, agents useful for diagnostic purposes may also be delivered into and/or through the body surface using the present method.The invention is also useful as a non-invasive diagnostictechnique, i.e., in enabling the sampling of physiologic material from beneath the skin or other body surface and into a collection (and/or evaluation) chamber.The present invention will employ, unless otherwise indicated, conventional pharmaceutical methodology and more specifically conventional methodology used in connection with transdermal delivery of pharmaceutically active compounds and enhancers.In describing the present invention, the following terminology will be used in accordance with the definitions set out below.A "biological membrane" is intended to mean a membrane material present within a living organism which separates one area of the organism from another and, more specifically, which separates the organism from its outer environment. Skin and mucous membranes are thus included."Penetration enhancement" or "permeation enhancement" as used herein relates to an increase in the permeability of skin to a material such as a pharmacologically active agent, i.e., so as to increase the rate at which the material permeates into and through the skin. The present invention involves enhancement of permeation through the use of ultrasound, and, in particular, through the use of ultrasound having a frequency of greater than 10 MHz."Transdermal" (or "percutaneous") shall mean passage of a material into and through the skin to achieve effective therapeutic blood levels or deep tissue therapeutic levels. While the invention is described herein primarily in terms of "transdermal" administration, it will be appreciated by those skilled in the art that the presently disclosed and claimed methodalso encompasses the "transmucosal" and "topical" administration of drugs using ultrasound. "Transmucosal" is intended to mean passage of any given material through a mucosal membrane of a living organism and more specifically shall refer to the passage of a materialfrom the outside environment of the organism, through a mucous membrane and into the organism. "Transmucosal" administration thus includes delivery of drugs through either nasal or buccal tissue. By "topical" administration is meant local administration of a topical pharmacologically active agent to the skin as in, for example, the treatment of various skin disorders or the administration of a local anaesthetic. "Topical" delivery can involve penetration of a drug into the skin but not through it, i.e., topical administration does not involve actual passage of a drug into the bloodstream."Carriers" or "vehicles" as used herein refer to carrier materials without pharmacological activity which are suitable for administration with other pharmaceutically active materials, and include any such materials known in the art, e.g., any liquid, gel, solvent, liquid diluent, solubilizer, or the like, which is nontoxic and which does not interact with the drug to be administered in a deleterious manner. Examples of suitable carriers for use herein include water, mineral oil, silicone, inorganic gels, aqueous emulsions, liquid sugars, waxes, petroleum jelly, and a variety of other oils and polymeric materials.By the term "pharmacologically active agent" or "drug" as used herein is meant any chemical material or compound suitable for transdermal or transmucosal administration which can either (1) have a prophylactic effect on the organism and prevent an undesired biological effect such as preventing aninfection, (2) alleviates a condition caused by a disease such as alleviating pain caused as a result of a disease, or (3) either alleviates or completely eliminates the disease from the organism. The effect of the agent may be local, such as providing for a local anaesthetic effect or it may be systemic. Such substances include the broad classes of compounds normally delivered through body surfaces and membranes, including skin. In general, this includes: anti-infectives such as antibiotics and antiviral agents; analgesics and analgesic combinations; anorexics; antihelminthics; antiarthritics; antiasthmatic agents; anticonvulsants; antidepressants; antidiabetic agents; antidiarrheals; antihistamines; antiinflammatory agents; antimigraine preparations; antinauseants; antineoplastics; antiparkinsonism drugs; antipruritics; antipsychotics; antipyretics; antispasmodics; anticholinergics; sympathomimetics; xanthine derivatives; cardiovascular preparations including potassium and calcium channel blockers, beta-blockers, and antiarrhythmics; antihypertensives; diuretics; vasodilators including general coronary, peripheral and cerebral; central nervous system stimulants; cough and cold preparations, including decongestants; hormones such as estradiol and other steroids, including corticosteroids; hypnotics; immunosuppressives; muscle relaxants; parasympatholytics; psychostimulants; sedatives; and tranquilizers. By the method of the present invention, both ionized and nonionzed drugs may be delivered, as can drugs of either high or low molecular weight.Proteinaceous and polypeptide drugs represent a preferred class of drugs for use in conjunction with the presently disclosed and claimed invention. Such drugs cannot generally be administered orally in that they Are often destroyed in the G.I.tract or metabolized in the liver. Further, due to the high molecular weight of most polypeptide drugs, conventional transdermal delivery systems are not generally effective. It is also desirable to use the methodof the invention in conjunction with drugs to which the permeability of the skin is relatively low, or which give rise to a long lag-time (application of ultrasound as described herein has been found to significantly reduce the lag-time involved with the transdermal administration of most drugs).By a "therapeutically effective" amount of a pharmacologically active agent is meant a nontoxic but sufficient amount of a compound to provide the desired therapeutic effect. The desired therapeutic effect may be a prophylactic effect, in preventing a disease, an effect which alleviates a system of the disease, or a curative effect which either eliminates or aids in the elimination of the disease.As noted above, the present invention is a method for enhancing the rate of permeation of a drug through an intact area of an individual's body surface, preferably the human skin. The method involves transdermal administration of a selected drug in conjunction with ultrasound. Ultrasound causes thermal, mechanical and chemical alterations of biological tissue, thereby enhancing the rate of permeation of a given material therethrough.While not wishing to be bound by theory, applicants propose that the use of higher frequency ultrasound as disclosed herein specifically enhances the permeation of the drug through the outer layer of skin, i.e., the stratum corneum, by causing momentary and reversible perturbations within (and thus short-term, reversible reduction in the barrier function of) the layer ofthe stratum corneum. It will be appreciated by those skilled in the art of transdermal drug delivery that a number of factors related to the present method will vary with the drug to be administered, the disease or injury to be treated, the age of the selected individual, the location of the skin to which the drug is applied, and the like.As noted above, "ultrasound" is ultrasonic radiation of a frequency above 20,000 Hz. As may be deduced from the literature cited above, ultrasound used for most medical purposes typically employs frequencies ranging from 1.6 to about 10 MHz. The present invention, by contrast, employs ultrasound frequencies of greater than about 10 MHz, preferably in the range of about 15 to 50 MHz, most preferably in the range of about 15 to 25 MHz. It should be emphasized that these ranges are intended to be merely illustrative of the preferred embodiment; in some cases higher or lower frequencies may be used.The ultrasound may be pulsed or continuous, but is preferably continuous when lower frequencies are used. At very high frequencies, pulsed application will generally be preferred so as to enable dissipation of generated heat.The preferred intensity of the applied ultrasound is less than about 5.0 W/cm.sup.2, more preferably is in the range of about 0.01 to 5.0 W/cm.sup.2, and most preferably is in the range of 0.05 to 3.0 W/cm.sup.2. The total treatment time, i.e., the period over which drug and ultrasound are administered, will vary depending on the drug administered, the disease or injury treated, etc., but will generally be on the order of about 30 seconds to 60 minutes, preferably 5 to 45 minutes, more preferably 5 to 30 minutes, and most preferably 5 to 10minutes. It should be noted that the aforementioned ranges represent suggested, or preferred, treatment times, but are not in any way intended to be limiting. Longer or shorter times may be possible and in some cases desirable. Virtually any type of device may be used to administer the ultrasound, providing that the device is callable of producing the higher frequency ultrasonic waves required by the present method. A device will typically have a power source such as a small battery, a transducer, a reservoir in which the drug medium is housed (and which may or may not be refillable), and a means to attach the system to the desired skin site.As ultrasound does not transmit well in air, a liquid medium is generally needed to efficiently and rapidly transmit ultrasound between the ultrasound applicator and the skin. As explained by P. Tyle et al., cited above, the selected drug medium should contain a "coupling" or "contacting" agent typically used in conjunction with ultrasound. The coupling agent should have an absorption coefficient similar to that of water, and furthermore be nonstaining, nonirritating to the skin, and slow drying. It is clearly preferred that the coupling agent retain a paste or gel consistency during the time period of ultrasound administration so that contact is maintained between the ultrasound source and the skin. Examples of preferred coupling agents are mixtures of mineral oil and glycerine and propylene glycol, oil/water emulsions, and a water-based gel. A solid-state, non-crystalline polymeric film having the above-mentioned characteristics may also be used. The drug medium may also contain a carrier or vehicle, as defined alone.A transdermal patch as well known in the art may be used in conjunction with the present invention, i.e., to deliver the drugmedium to the skin. The "patch", however, must have the properties of the coupling agent as described in the preceding paragraph so as to enable transmission of the ultrasound from the applicator, through the patch, to the skin.As noted earlier in this section, virtually any chemical material or compound suitable for transdermal, transmucosal or topical administration may be administered using the present method. Again, the present invention is particularly useful to enhance delivery of proteinaceous and other high molecular weight drugs.The method of the invention is preferably carried out as follows. The drug medium, i.e., containing the selected drug or drugs in conjunction with the coupling agent and optionally a carrier or vehicle material, is applied to an area of intact body surface. Ultrasound preferably having a frequency greater than about 10 MHz may be applied before or after application of the drug medium, but is preferably applied immediately before application of the drug so as to "pretreat" the skin prior to drug administration.It should also be pointed out that the present method may be used in conjunction with a chemical permeation enhancer as known in the art, wherein the ultrasound enables the use of much lower concentrations of permeation enhancer--thus minimizing skin irritation and other problems frequently associated with such compounds--than would be possible in the absence of ultrasound. The permeation enhancer may be incorporated into the drug medium or it maybe applied in a conventional transdermal patch after pretreatment of the body surface with ultrasound.The present invention may also be used in conjunction with。
羟基自由基测定
Quantitation of hydroxyl radical during Fenton oxidationfollowing a single addition of iron and peroxideMichele E.Lindsey,Matthew A.Tarr*Department of Chemistry,University of New Orleans,New Orleans,LA 70148,USAReceived 2October 1998;accepted 15July 1999AbstractChemical probes were used to study the formation of hydroxyl radical in aqueous iron±hydrogen peroxide reaction.Hydroxyl radical formation rate and time dependent concentration were determined in pure water,in aqueous fulvic acid (FA)and humic acid (HA)solutions,and in natural surface waters.Indirect determinations of hydroxyl radical were made by quantitating hydroxyl radical reactions with probe compounds under controlled conditions.High probe concentrations were used to determine radical formation rates and low probe concentrations were used to determine time dependent radical concentration.Two independent probes were used for intercomparison:benzoic acid and 1-propanol.Good agreement between the two probes was observed.Natural water matrices resulted in lower radical formation rates and lower hydroxyl radical concentrations,with observed formation rate and yield in natural waters up to four times lower than in pure water.HA and FA also reduced hydroxyl radical formation under most conditions,although increased radical formation was observed with FA at certain pH values.Hydroxyl radical formation increased linearly with hydrogen peroxide concentration.Ó2000Elsevier Science Ltd.All rights reserved.Keywords:Fenton oxidation;Hydroxyl radical;Degradation;Iron;Hydrogen peroxide;Natural water1.IntroductionNumerous studies have investigated the use of Fen-ton chemistry for pollutant degradation or remediation (Graf et al.,1984;Puppo,1992;Yoshimura et al.,1992;Zepp et al.,1992).In these applications,hydrogen per-oxide is converted to hydroxyl radical in a catalytic cycle with cationic iron acting as catalyst.The high reactivity of hydroxyl radical is advantageous since it readily de-grades a wide array of pollutants (reaction with alkanes,k 107±109M À1s À1;reaction with alkenes and aro-matics,k 109±1010M À1s À1).Unfortunately this ad-vantage is also an important drawback since the hydroxyl radical often reacts with non-pollutant species present at higher concentration.Furthermore,the cata-lytic cycle is in¯uenced by pH,iron complexation,iron solubility,and iron redox cycling between the +2and +3states.In order to better understand the use of Fenton chemistry for pollutant degradation in waste streams or contaminated sites,a better understanding of matrix e ects is needed.This report focuses on the e ects of natural water matrices on hydroxyl radical formation and scavenging.Iron/peroxide systems have been used to degrade a number of contaminants,mostly in the aqueous phase.Degradation of the herbicides 2,4-D,2,4,5-T,and atr-azine in aqueous solution by Fe (II)/H 2O 2or Fe (III)/H 2O 2has been reported (Pignatello,1992).Reactions were pH sensitive,and acidic conditions were necessary for iron solubility.Vella and Munder (1993)used Fe (II)/H 2O 2for the degradation of phenolic compounds in water.Again,acidic conditions (pH 4)were used.Although complete elimination of the parent compound could be achieved for chlorinated and otherphenols,Chemosphere 41(2000)409±417*Corresponding author.Fax:+1-504-280-6860.E-mail address:mtarr@ (M.A.Tarr).0045-6535/00/$-see front matter Ó2000Elsevier Science Ltd.All rights reserved.PII:S 0045-6535(99)00296-9the presence of phosphate signi®cantly hindered degradation.To allow reaction at near neutral pH,researchers have utilized iron chelating agents(Sun and Pignatello, 1992,1993).Several iron chelates were found to be ac-tive in Fenton oxidation although the chelator was also degraded at a slower rate(Sun and Pignatello,1992). Naturally occurring compounds can act as metal che-lators.For example,inorganic salts,humic acids(HAs), fulvic acids(FAs),and organic colloids have been shown to exhibit signi®cant metal complexation(Pettersson et al.,1997;Ganguly et al.,1998;Klein and Niessner, 1998;Rose et al.,1998;Roux et al.,1998).Commercial applications of Fenton chemistry to remediation of contaminated soil are currently in use. These methods add both iron and peroxide to the sat-urated zone,and utilize iron chelators and peroxide stabilizers(Watts and Dilly,1996;Greenburg et al., 1997).Such applications have been successful in reme-diating the saturated zone after petroleum leakage from an underground storage tank.However,conditions for such remediation have typically been developed from empirical observations of degradation e ciency rather than from a fundamental understanding of the HOádynamics.Furthermore,a large excess of peroxide is often used.Fenton reagents have also been used for degradation of bio-recalcitrant perchloroethylene(PCE)and poly-chlorinated biphenyls(PCBs)adsorbed on sand(Sato et al.,1993).Treatment required adjustment of the pH to3with degradation severely limited at pH7.Even at optimum pH,PCB treatment still yielded chlorinated degradation products,indicating incomplete degrada-tion.Further studies on degradation of PCBs indicated that dissolved PCBs are much more readily degraded by hydroxyl radical than are PCBs sorbed to sand(Sedlak and Andren,1994).Some studies involving soil/water systems have re-lied on naturally occurring iron in soils to react with added H2O2(Croft et al.,1992;Watts et al.,1993). However,water insoluble pollutants adsorb to the surface of soil particles thus impeding degradation.Due to the di culty of oxidation across the liquid±solid boundary,high stoichiometric amounts of H2O2were required to achieve complete degradation of the pol-lutants in these environments(Watts et al.,1993). Again,a lack of understanding of the HOáand pollu-tant degradation dynamics was overcome in these sys-tems simply by using an excess of peroxide,rather than adjusting other parameters to optimize the degradation e ciency.The e ciency of hydroxyl radical production from peroxide is a ected by a number of factors,including pH,iron oxidation state,and iron chelation.Phosphate has been reported to inhibit hydroxyl radical production (Vella and Munder,1993),and additional reports indi-cate either inhibition(Croft et al.,1992)or acceleration (Puppo,1992)of HOáproduction in the presence of various ligands.Once formed,hydroxyl radicals may be lost through reaction with matrix mon matrices include FA and HA in natural freshwaters,as well as inorganic species in brackish waters.Due to the relatively high concentration of matrix species,generally only a small fraction of the radicals formed can react with the pol-lutant.This process is a major limitation of Fenton chemistry for degradation of pollutants in the presence of matrix constituents,and results in increased peroxide demand and higher costs.Although signi®cant research has focused on Fenton systems and quantitation of hydroxyl radical concen-tration,several important issues have not yet been ad-dressed.Some researches(Ravikumar and Gurol,1994; Lin and Gurol,1998)have measured loss of hydrogen peroxide as an indicator for hydroxyl radical formation. This approach is not entirely su cient because not all peroxide degraded is converted to hydroxyl radical,and hence measurement of peroxide loss does not allow di-rect determination of[HOá].Other researchers have measured hydroxyl radical concentration under steady state[HOá]conditions,primarily in photochemical sys-tems(Haag and Hoign e,1985;Zhou and Mopper, 1990).While this approach is applicable to photo-chemical systems,it is not representative of common Fenton systems in which peroxide is added in a single dose,resulting in non-steady state[HOá].Additional studies have attempted to quantitate hydroxyl radical under non-steady state conditions(Tomita et al.,1994; Mizuta et al.,1997);however,due to a number of fac-tors,these reports did not provide conclusive hydroxyl radical information.In this study,chemical probes were used to measure both hydroxyl radical formation rate and time depen-dent hydroxyl radical concentration under non-steady state conditions.Methods were developed that allow these determinations in pure water and natural waters, allowing assessment of the role of natural matrices on Fenton oxidations.2.ExperimentalMaterials.Puri®ed water was obtained by further puri®cation of distilled water with a NanopureUV (Barnstead)water treatment system.Natural water samples were collected from sites in Southeast Louisiana at Crawford Landing(CL)on the West Pearl River and from a small water body connecting Lake Pontchartrain and Lake Maurepas(LM).The LM water contained a higher concentration of dissolved organic carbon and inorganic species than the CL water.All natural water samples were®ltered using pre-combusted0.5l m glass410M.E.Lindsey,M.A.Tarr/Chemosphere41(2000)409±417®ber®lters(Machery±Nagel,Rund®lter MN,Alberta, Canada)and were stored in the dark at4°C.Natural water samples were used directly or were diluted with pure water.Suwannee River FA and HA standard ma-terials were purchased from the International Humic Substances Society.FA and HA concentrations are reported as mg FA lÀ1and mg HA lÀ1.The carbon content of these materials are52.44%and52.55%by weight,respectively.Hydrogen peroxide(EM science,$30%)was stan-dardized using iodometric titration(Christian,1994). Iron(II)perchlorate(99+%)was purchased from Alfa. Benzoic acid(BA)(99.5+%),p-hydroxybenzoic acid (99+%),and2,4-dinitrophenylhydrazine(DNPH)(70%) were purchased from Aldrich.Propionaldehyde(98%) was purchased from Fluka,and1-propanol(PrOH) (99+%)was purchased from Mallinkrodt.Dimethyl sulfoxide(certi®ed ACS)and acetonitrile(HPLC grade) were obtained from Fisher.All reagents were used as received.Hydroxyl radical trapping.Both benzoic acid and n-propanol were used as probes for hydroxyl radical. Benzoic acid has a known reaction rate constant of 4.2´109MÀ1sÀ1with hydroxyl radical in aqueous media(Buxton et al.,1988).This reaction produces p-hydroxybenzoic acid(p-HBA)as well as o-HBA, m-HBA,and other products.The fraction of p-HBA produced per reaction was taken from(Zhou and Mopper,1990),who reported5X87Æ0X18moles HOáreacted per mole p-HBA produced.1-Propanol reacts with hydroxyl radical in aqueous media at a rate of 2.8´109MÀ1sÀ1to form propionaldehyde in46%yield (Buxton et al.,1988).BA or PrOH solutions of various concentrations were prepared in pure and natural water.At time zero, a single dose of hydrogen peroxide and a single dose of Fe(II)were added with vigorous mixing.These additions resulted in time zero concentrations of 0.2±1.0mM H2O2and0.2±0.53mM Fe(II).Reactions were stirred,kept in the dark,and maintained at20°C. After a given time interval,reactions were quenched by addition of a su cient amount of a quencher that e ectively outcompeted the probe molecule for reaction with hydroxyl radical.For benzoic acid probe studies, 0.5ml of PrOH was added per10ml of reaction solution.For PrOH probe studies,4ml of dimethyl sulfoxide(DMSO)containing5mM DNPH were added per10ml of reaction solution.These amounts of added quencher had rates of reaction with hydroxyl radical of 50±5600times greater than the probe;therefore,it was assumed that upon addition of quencher,no signi®cant reaction of probe with hydroxyl radical occurred.The resulting products of probe-hydroxyl radical reaction were then analyzed as described below.Each of these experiments produced a single time point.Repetition of the experiment for di erent times then enabled recon-struction of time dependent data from the individual experiments.Quantitation of products.Reaction products were quantitated by high performance liquid chromatography using a Hewlett-Packard1090liquid chromatograph.A Spherisorb ODS-2column(5l m particle size,25cm length´4.6mm id)was used for all separations.Benzoic acid and hydroxybenzoic acids were sepa-rated using the following procedure(Zhou and Mopper, 1990).Samples were brought to pH2±3using HCl then loaded onto a1.5ml loop.After injection,the analytes were pre-concentrated on-column during the initial 3min,then were eluted by increasing the solvent strength.The elution gradient was:water at pH$2.5(A) and acetonitrile(B);0±3min15%B,3±13min linear to 75%B,13±15min linear to100%B.The¯ow rate was 1.0ml minÀ1.Analytes were detected by absorbance at 254nm.For natural water samples it was necessary to ®lter the samples before injection to remove particulates. This was accomplished by raising the pH to P8using NaOH then passing the sample through a0.2l m nylon ®lter(Cole Parmer).The pH adjustment eliminated loss of benzoic acid and hydroxybenzoic acids on the®lters by forming the more soluble ionized species.After®l-tration,the pH was re-adjusted to2±3using HCl and the sample was analyzed as above.Both benzoic acid and p-hydroxybenzoic acid were stable under these condi-tions over the time required for analysis.Propionaldehyde,the product of1-propanol reac-tion with hydroxyl radical,was quantitated following derivitization with DNPH(Coutrim et al.,1993).The derivitization was carried out by adding5mM DNPH in DMSO and allowing12h for the derivitization to occur.Extended time periods(up to48h)did not a ect the concentration of propionaldehyde detected. The derivitized product was injected using a50l l loop.The elution gradient was:water(A)and aceto-nitrile(B);0±2min50%B,2±16min linear to100% B.The analytes were detected by absorbance at 254nm.Hydrogen peroxide determination.Hydrogen peroxide was determined by titration(Christian,1994).In this method,excess IÀplus a catalyst was added to the hy-drogen peroxide solution to form IÀ3.The IÀ3was then titrated with thiosulfate.Hydrogen peroxide was quantitated at di erent times after addition of Fe2 ,and it was assumed that any further Fenton reaction was quenched upon the addition of excess IÀ.3.Results and DiscussionHydroxyl radical quantitation.In a system with both sources and sinks for hydroxyl radical,the change in [HOá]with respect to time is described by Zhou and Mopper(1990):M.E.Lindsey,M.A.Tarr/Chemosphere41(2000)409±417411d HO áa d t F Àk p HO áP Àk S i HO á S iÀk HO HO á 21where F is the formation rate of hydroxyl radical,and the remaining negative terms are loss due to reaction with probe (P),with scavengers (S),and self reaction,respectively.This equation does not represent steady state conditions,but rather the rate of change in hy-droxyl radical concentration with respect to time.Therefore,this equation is applicable under non-steady state conditions.As [P]increases,the term Àk p HO á P will dominate the loss terms.Under these conditions,the total moles of P reacted will be stoichiometrically related to the total moles of HO áformed (Blough,1988),provided that the reaction product does not react signi®cantly with hy-droxyl radical.Since in this study product concentration was always considerably lower than the probe concen-tration,we assumed no signi®cant loss of product due to hydroxyl radical reaction.In the case of low probe concentrations,if [P]is small enough so that k p HO á P ( S i HO áS i k HO HO á 2,then d HO á a d t will be relatively una ected by the probe.In such cases,the concentration of hydroxyl radical in the absence of the probe can be calculated from the second order rate law R p k p HO á P 2 HO á R p a f k p P g 3 HO á avg R p a f k p P avg g4where R p is the rate of probe reaction,k p is the second order rate constant,and avg indicates time averaged values.Over short time intervals,the value for R p was calculated from the linear change in the concentration of the product resulting from probe-HO áreaction.This approach is valid when [HO á]and [P]do not change signi®cantly in the time interval.Validation of experimental approach .In order to con®rm that the approach used here is valid,several experiments were undertaken.The ®rst set of experi-ments involved measurement of product yield as a function of probe concentration.These experiments al-lowed de®nition of high probe concentrations (useful for determination of total HO áformation)and low probe concentration (useful for determination of HO ácon-centration with minimal perturbation by the probe).Product formation was quantitated as a function of re-action time for several probe concentrations.Data for benzoic acid experiments in several matrices are pre-sented in Fig.1.In all matrices,as the benzoic acid concentration increased,the amount of product in-creased,indicating that higher concentrations of benzoic acid were better able to outcomplete the naturalscavengers for reaction with HO á.At su ciently high benzoic acid concentrations,further increases in con-centration resulted in little increase in product yield,as seen by a plateau in the curves in Fig.1at higher [BA].Such behavior has been observed previously (Tomita et al.,1994).These data indicate that no additional trapping of HO ácould be achieved by increasing [BA],and therefore at these concentrations the benzoic acid must be trapping essentially all of the HO á.Under these conditions,the total moles of product obtained is directly proportional to the total moles HO áproduced (for benzoic acid,the proportionality factor is 5.9(Zhou and Mopper,1990)).Increased content of LM water resulted in a lower total amount of HO átrapped in the plateau region (above 5mM BA).This result is most likely due to a decrease in the e ciency of radical production in the presence of the natural water matrix.This result was also evident in time dependent measurements of total HO áproduced,as will be discussed below.As the benzoic acid concentration was lowered,the yield of product decreased.In order to determine hy-droxyl radical concentration in the absence of the added probe,it was necessary that the probe had a negligible e ect on hydroxyl radical concentration.We used the ratio of product yield at low [BA]to product yield at the high [BA]plateau to determine the extent of perturba-tion caused by the addition of benzoic acid.For exam-ple,in a 50/50mixture of pure water with LM water,0.5mM BA has a product yield of only 4%of the yield for P 5mM BA.In contrast,the product yield for 0.5mM BA in pure water was 40%of the yield at 5mM BA.Based on these results,we selected benzoic acid concentrations for use in further experiments to deter-mine HO áproduction and HO áconcentration.For HO áproduction,we used benzoic acid concentrations intheFig.1.Moles of hydroxyl radical trapped as a function of probe concentration (benzoic acid)in pure water and several dilutions of LM water.All data were acquired 10min after the addition of iron (II)perchlorate and H 2O 2at time zero concentrations of 0.2and 0.5mM,respectively.412M.E.Lindsey,M.A.Tarr /Chemosphere 41(2000)409±417plateau region(typically9mM),and for[HOá]mea-surements we used benzoic acid concentrations that had product yields of less than10%of the maximum yield on the plateau(typically0.2mM).Also illustrated in Fig.1is the e ect of increased matrix components on HOáscavenging.As the per-centage of natural water increased,higher concentra-tions of benzoic acid were required to reach the plateau region.These results indicate the higher level of scav-engers in the natural water,therefore requiring a higher benzoic acid concentration to trap all of the hydroxyl radical formed.The presence of these scavengers also minimized the perturbation at low benzoic acid concentrations.Similar studies using propanol as probe were also conducted,and the results are presented in Fig.2.For pure water,complete trapping could be achieved above 100mM PrOH.In contrast to the benzoic acid probe, propanol did not signi®cantly perturb the[HOá]with propanol concentrations below$2mM.For LM water, the PrOH product yield did not plateau as was observed for benzoic acid.Even with propanol concentrations as high as1M,the product yield did not plateau.Therefore PrOH was not used to determine formation rate of HOáin natural waters.However,measurement of[HOá]in natural water was deemed feasible at propanol concen-trations below$10mM.The use of higher concentra-tions of PrOH as compared to benzoic acid is likely a result of the lower rate constant for propanol reaction with hydroxyl radical.Propanol and benzoic acid are distinct probes with di erent mechanisms of reaction with hydroxyl radical. We used such distinct probes to eliminate any possible bias of a single parison of the BA and PrOH results under the same conditions showed good agree-ment.These results can be seen in Fig.3,and are dis-cussed further below.The strong agreement between data from these distinct probes indicate that the probes introduced little or no bias into these measurements.For example,complexation of iron by benzoic acid was de-termined to be insigni®cant,as any such interaction would have resulted in divergent results for the two probes.Measurement of HOáProduction.Hydroxyl radical production was measured in pure water,CL water,LM water,and aqueous solutions of Suwannee River HA and FA.For these experiments,benzoic acid was used as probe at a concentration of9mM(pH$3).The total moles of HOáproduced was measured as a function of time after a single addition of Fe(II)and H2O2.A comparison of moles HOáproduced as a function of time for pure water and the two natural waters is pre-sented in Fig.4.The CL water matrix showed slightly lower HOáproduction than pure water,and the LM water matrix showed dramatically lower production than pure water.After20min,the reaction in pure water had produced$3X5Â10À6mol of HOá,while in CL water only$3Â10À6mol HOáwere produced,and in LM water only$0X8Â10À6moles HOáwere produced. These data indicate that the natural water matrices used here resulted in a lower e ciency of hydroxyl radical formation compared to pure water.Observed rates of formation of hydroxyl radical were also lower in the natural waters than in pure water.We measured the initial rates of hydroxyl radical formation from the ini-tial slopes of the curves in Fig.4,and the resulting values are presented in Table1.Suwannee River HA and FA also showed decreased hydroxyl radical formation.Fig.5illustrates the for-mation of HOávs time for various concentrations of HA and FA.HA caused a more dramatic decrease inradicalFig.2.Moles of hydroxyl radical trapped as a function ofprobe concentration(PrOH)in pure water and dilutions of LMwater.All data were acquired10min after the addition of iron(II)perchlorate and H2O2at time zero concentrations of0.2and0.5mM,respectively.The x-axis is presented with a loga-rithmic scale due to the large range of propanol concentrationsused.Fig.3.Measured time dependent hydroxyl radical concentra-tion(symbols)based on reaction with benzoic acid(0.2mM,pH 4.3)or PrOH(1mM,pH 6).Curves are polynomial®tsto the data points.Matrix is CL water.M.E.Lindsey,M.A.Tarr/Chemosphere41(2000)409±417413production than FA.The initial rate of hydroxyl radical production was decreased by 11%in the presence of 30mg l À1FA and by 27%in the presence of 30mg l À1HA.For HA,the initial hydroxyl radical production rate showed a linear decrease over the range of HA concentrations studied,as illustrated in Fig.6.Since the FA and HA solutions (with 9mM BA)were very close in pH to pure water (with 9mM BA),and since no additional inorganic species were present,these data indicate that dissolved natural organic matter can have a dramatic e ect on hydroxyl radical formation as well as scavenging.Hydroxyl radical formation was assessed as a func-tion of pH with and without added FA.The total moles of HO áformed was measured at 20and 300s after mixing Fe 2 and peroxide.Fig.7represents total moles of HO áformed in a 300s time interval as a function of pH and FA content.The highest yield of hydroxyl radical was observed at pH 3.1,which is in good agreement with previous studies (Pignatello,1992).At this pH,addition of FA resulted in a slight decrease in radical production.However,as the pH was increased,the FA had the opposite e ect,with increased radical production at increased [FA].Furthermore,the e ect of pH was minimized at the highest FA concentration.The data for a 20s time interval showed similar results.The distribution of Fe 2 and Fe 3 is sensitive to pH,with the Fe 2 state becoming less stable with increasing pH,and the formation of oxides and hydroxides also increases with increasing pH.It is therefore reasonable to expect,as has been previously observed (Pignatello,1992),that Fenton production of hydroxylradicalFig.6.Initial rate of hydroxyl radical formation as a function of HA concentration.Benzoic acid used as probe at 9mM,(pH $3).Fig.5.Total moles of HO áformed as a function of time for aqueous FA (a)and HA (b)solutions.Benzoic acid used as probe at 9mM (pH $3).Fig.4.Total moles of HO áformed as a function of time for pure water (pH 3.1),CL water (pH 3.3),and LM water (pH 3.6).Benzoic acid used as probe at 9mM.Table 1Observed initial rate for hydroxyl radical formation in pure water and natural waters Water Initial rate (M s À1)DOC a (mg C l À1)Puri®ed 1.2´10À6<0.003CL 1.0´10À629.9LM0.3´10À6123aDissolved organic carbon.414M.E.Lindsey,M.A.Tarr /Chemosphere 41(2000)409±417becomes less e cient at higher pH.Also previously observed is that iron chelation minimizes these pH ef-fects by stabilizing the chelated Fe 2 ion (Sun and Pig-natello,1993).Our results provide evidence that iron chelation by FA results in stabilization of Fe 2 with respect to pH.At low pH,Fe 2 stability is high,and any chelation of iron by FA has only a small e ect on HO áformation.At higher pH,chelation by FA likely results in increased Fe 2 stability,resulting in a marked increase in Fenton reaction yield upon addition of FA.Previous reports have indicated pseudo ®rst order loss of H 2O 2in the presence of Fe (II)(Walling,1975),Fe (III)+light (Pignatello,1992),and iron oxides (Lin and Gurol,1998).Our peroxide data also indicate ®rst order behavior,although the kinetic behavior did not stabilize until 30±60s after the addition of peroxide.An illustration of this behavior is given in Fig.8.Previous studies did not monitor kinetics at such short times.Our observations were consistent over a wide range of per-oxide concentrations (5±100mM).A possible explana-tion is that initially all of the iron is present as Fe 2 ,which can react with H 2O 2to form HO á.As this reaction proceeds,the concentration of Fe 2 declines,and con-sequently the rate of H 2O 2consumption and HO áfor-mation decline.The loss of Fe 2 is eventually balanced by formation of Fe 2 through reduction of Fe 3 by re-action with peroxide or hydroperoxyl radical,and a steady state Fe 2 concentration is reached.At this point (>60s),pseudo ®rst order loss of H 2O 2is observed.This explanation is also supported by evidence that the HO áformation rate is signi®cantly higher in the ®rst 60s.The in¯uence of hydrogen peroxide concentration on hydroxyl radical production was also assessed.The moles of HO áformed increased linearly with increasing [H 2O 2].The hydroxyl radical formation was measured at20s and 300s intervals after mixing Fe 2 and H 2O 2.The data are presented in Fig.9.The slope of the line was greater at 300s than at 20s,indicating that increasing H 2O 2concentration will result in more signi®cant in-creases in hydroxyl radical over longer time periods.The above observations could be used in evaluating the e ciency of Fenton oxidation in a given matrix.Three possible explanations exist for the observed dif-ferences in the natural water matrices:(1)the rate of peroxide reaction with iron may be altered by iron complexation (Croft et al.,1992;Puppo,1992)with matrix components,(2)Fe (II)/Fe (III)redox cycling may be altered by complexation (Croft et al.,1992)or by the presence of oxidants /reductants in the matrix,or (3)peroxide may be consumed by reaction with matrix components.This method provides a basic understand-ing of the time dependent radical formation rate and allows direct assessment of matrix e ects onradicalFig.8.Plot of ln[H 2O 2]vs time after addition of peroxide to solution of 0.5mM Fe 2 (aq).Line is linear regression to the data points for t P 60s.Fig.9.Total moles of HO áformed as a function of hydrogen peroxide concentration.Benzoic acid used as probe at 9mM (pH 3.1).Measurements made 20and 300s after mixing Fe 2 and H 2O 2in purewater.Fig.7.Total moles of HO áformed as a function of pH for pure water and aqueous FA.Benzoic acid used as probe at 9mM.Lower pH was achieved by addition of perchloric acid,and higher pH was achieved by addition of NaOH.Measurements made 300s after mixing Fe 2 and H 2O 2.M.E.Lindsey,M.A.Tarr /Chemosphere 41(2000)409±417415。
生物质材料对水体中染料和其他有机污染物的吸附
文章编号：1672-2019（2009）01-0019-05·综述·生物质材料对水体中染料和其他有机污染物的吸附顾迎春1，郑静2，石碧1（1.四川大学制革清洁技术国家工程实验室，四川成都610065；2.成都信息工程学院图书馆，四川成都610225）摘要：大量研究表明：纤维素基生物质、甲壳素和微生物对水体中染料的吸附容量低于商品活性碳对染料的吸附容量；虽然壳聚糖对一些阴离子型染料有相当大的吸附容量，但由于其性能不稳定，因此难以获得大规模工业应用。
关于生物质对其他有机污染物吸附性能的研究报道相对较少，说明这方面的研究有待于进一步深入和拓展。
废弃皮胶原是一类来源极其丰富的生物质，近年来的研究发现：基于皮胶原研制的新型吸附剂对水体中的阴离子型染料和有机酸能有效去除，有可能在染料和有机废水处理方面得到应用。
关键词：生物质，吸附，染料，有机污染物，皮胶原中图分类号：TQ028文献标识码：Adsorption of dyes and other organic pollutants on biomassmaterials from aqueous solutionsGU Ying-chun 1,ZHENG Jing 2,SHI Bi 1(1.National Engineering Laboratory for Clean Technology of Leather Manufacture,Sichuan University,Chengdu 610065,China;2.Library of Chengdu University of Information andTechnology,Chengdu,610225,China)Abstract ：A large number of researches have indicated that the adsorption capacities of dyes on cellulose-based biomass,chitin and microbe were lower than those on commercial activated carbons from aqueous solutions.Al －though the adsorption capacities of some anionic dyes on chitosan were great considerably,the properties of chitosan were not stable enough to acquire the industrial application on large scale.The relatively fewer reports illustrate that there should be more profound and extended research concerned with the adsorption characteristics of other organic pollutants on biomass.Waste hide collagen is a type of very abundant biomass.The recent investigation has found that a novel adsorbent based on hide collagen had the effective removal of anionic dyes and organic acids from aqueous solutions and might have the potential usefulness on the treatment of dye and organic wastewater.Key words ：biomass,adsorption,dyes,organic pollutions,hide collagen收稿日期：2008-12-07*基金项目:国家科技支撑计划课题（No.2006BAC02A09）；四川省重点科学与技术研究项目(04SG012-009)；四川大学青年科学基金(200452)[通讯作者]石碧，E-mail:shibi@ or sibitannin@ ，Tel:(028)85405508第17卷第1期中国医学工程Vol.17No.12009年3月China Medical EngineeringMar.2009对水体中染料和其他有机污染物吸附性能的研究的主要目的是对染料和有机废水进行脱色和净化处理。
关于环保的英语作文
Environmental protection is a critical issue that affects every individual on our planet.Here are some key points to consider when writing an essay on environmental conservation:1.Introduction to Environmental Issues:Begin by introducing the importance of environmental protection and the challenges our planet faces,such as climate change, deforestation,pollution,and loss of biodiversity.2.Causes of Environmental Degradation:Discuss the various factors contributing to environmental problems.This could include industrial activities,excessive use of fossil fuels,improper waste management,and overconsumption.3.Effects of Environmental Degradation:Explain the consequences of environmental damage,such as global warming,melting of polar ice caps,rising sea levels,and the extinction of species.4.Individual Actions for Environmental Protection:Emphasize the role of individuals in protecting the environment.Suggest actions like reducing,reusing,and recycling waste, conserving water and energy,and adopting a more sustainable lifestyle.ernment and Corporate Responsibility:Highlight the responsibility of governments and corporations in implementing policies and practices that promote environmental sustainability,such as regulating emissions,promoting renewable energy,and supporting reforestation efforts.6.Technological Innovations:Discuss the role of technology in environmental conservation,including advancements in renewable energy,electric vehicles,and sustainable materials.7.International Cooperation:Stress the importance of global cooperation in addressing environmental challenges.Mention international agreements and initiatives aimed at reducing pollution and protecting the environment,such as the Paris Agreement.cation and Awareness:Advocate for the importance of environmental education and raising public awareness about the need for conservation and sustainable practices.9.Case Studies:Include examples of successful environmental initiatives or communities that have made significant strides in environmental protection.10.Conclusion:Conclude by summarizing the main points and emphasizing the urgentneed for collective action to protect our environment for future generations. Remember to use persuasive language and provide evidence to support your arguments. Additionally,consider including a call to action,encouraging readers to take steps towards a more sustainable future.。
紫外辐射H2O2与PMS氧化准好氧矿化垃圾床渗滤液尾水
体系过程有机物降解有抑制作用并且对 2 体系的抑制尤为显著.在最优条件下(初始 pH 值为 3,氧化剂投量为 0.084mol/L),UV-H2O2 与 UV-PMS
体系处理后出水 COD 去除率分别达到了 72.09%和 56.22%.另外,UV-H2O2 体系中主要活性氧物种是羟基自由基,而 UV-PMS 体系中主要是由羟基自由
水(UV-H2O2)和紫外辐射过一硫酸盐(UV-PMS)体系对有机污染物的降解相比于单独体系效果显著.初始 pH 值和氧化剂投加量能够显著影响 2 种体系
的降解效能,增加氧化剂投加量能够一定程度提高 2 种体系对渗滤液尾水中有机物的去除;2 种体系均在酸性条件下效果较好,初始 pH 值的升高对 2 种
基和硫酸根自由基的共同作用.紫外-可见光谱与三维荧光光谱表明两体系中均能降解渗滤液尾水中难降解芳香类有机物质,并且 UV-PMS 较
UV-H2O2 体系对腐殖质的反应速率更快,但是两种体系对渗滤液尾水中腐殖质的降解途径存在显著差异.研究结果可为光化学氧化处理垃圾渗滤液中
难降解有机物提供参考.
关键词：紫外-过氧化氢；紫外-过一硫酸盐(UV-PMS)；准好氧矿化垃圾床；垃圾渗滤液；自由基
中国环境科学 2019,39(9)：3744~3753
China Environmental Science
紫外辐射 H2O2 与 PMS 氧化准好氧矿化垃圾床渗滤液尾水
冯 梅,陈炜鸣,潘旭秦,李启彬 1*,刘 丹 (西南交通大学地球科学与环境工程学院,四川 成都 611756)
摘要：采用紫外(UV)活化双氧水(H2O2)和过一硫酸盐(PMS)产生活性氧物种降解准好氧矿化垃圾床渗滤液尾水中有机污染物.结果表明,紫外辐射双氧
中图分类号：X703.1
211126695_环二鸟苷酸调控细菌胞外多糖生物合成的研究进展
于连升，葛菁萍，平文祥，等. 环二鸟苷酸调控细菌胞外多糖生物合成的研究进展[J]. 食品工业科技，2023，44（9）：422−430. doi:10.13386/j.issn1002-0306.2022060142YU Liansheng, GE Jingping, PING Wenxiang, et al. Research Progress on Regulation of Bacterial Exopolysaccharide Biosynthesis by Cyclic Diguanylate[J]. Science and Technology of Food Industry, 2023, 44(9): 422−430. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2022060142· 专题综述 ·环二鸟苷酸调控细菌胞外多糖生物合成的研究进展于连升1,2，葛菁萍1,2，平文祥1,2, *，杜仁鹏1,2,*（1.黑龙江大学生命科学学院，农业微生物技术教育部工程研究中心，黑龙江省寒区植物基因与生物发酵重点实验室，黑龙江省普通高校微生物重点实验室，黑龙江哈尔滨 150080；2.河北环境工程学院，河北省农业生态安全重点实验室，河北秦皇岛 066102）摘 要：细菌胞外多糖（Exopolysaccharide ，EPS ）是细菌生长代谢过程中自身合成并分泌到细胞壁外的一种次级代谢产物，可以调节细胞对不同基质的初始附着，保护细胞抗环境胁迫和脱水。
作为潜在的益生元，EPS 具有安全，无毒和特殊的理化性质，广泛应用在食品、医药、生物和工业等领域。
然而，细菌代谢系统复杂，EPS 的生物合成机制仍未得到全面解析。
环二鸟苷酸（Cyclic diguanylate ，c-di-GMP ）作为一类重要的第二信使，在细菌的生物被膜形成、运动性、黏附、毒力以及EPS 合成等众多生理活动上发挥重要的调控作用。
生物活性玻璃降解过程
| 50 |Smile Dental Journal | Volume 7, Issue 2 - 2012ABSTRACTThe development of new materials and methods to substitute lost parts or tissues to restore function and esthetics has been the goal and objective of human civilizations throughout history. Different materials have been proposed and applied to determine their biocompatibility and usefulness, avoiding any ejection, or at times unfavorable responses to foreign materials. With the new advances in the usage of different materials that can be used to restore bony defects, ranging from allografts to xenografts, the need was always to have synthetic material that can be used in such applications with unlimited supply. Bioactive glasses today are used widely in medical and dental fields. Bioactive glasses were used to coat dental implants, used as an antibiotic carrier, and used to restore periodontal defects. When applied to periodontal defects, it was found to be comparable to demineralized freeze-dried bone (DFDBA). The dissolution process is critical to all biomaterials because the cascade of events that will eventually lead to the induction or conduction of bone is dependent on the early chemical interaction between the biomaterials and the surrounding tissues. The bioactive glass possesses extra advantages over other available materials, such as risk free of disease transmission, unlimited supply and mechanical integrity. This article reviews the process of dissolution of Bioactive glasses when they interact with tissues at the time of placement until the complete resolution.KEYWORDSBioactive glasses, Dissolution, Silanol, Osteoconductive.Dissolution Process of Bioactive GlassesAhmad Akroof DDS, MSAl-Adan Dental Center, Head of Periodontal Unit – Kuwaitdntst999@INTRODUCTIONBioactive glasses are made usually of 45% SiO 2, 24.5% CaO, 24.5% Na 2O, and 6% P 2O 2; percentages are by weight.1 In addition to the previous composition, different compositions were also formulated to test the different reactivity rates of the bioactive materials.2 Some researchers have incorporated some porous polymers to bioactive glasses that mimic the bone/ cartilage interface. Others added CaF2 and Al2O3 to the bioactive glasses ceramics.3 New shapes were also developed such as the 45S5 Bioglass ® fiber network form.4MECHANISMThere are 11 steps for the interaction of bioactive glasses to bone as follows:1. Formation of Si-OH (silanol) bonds via cation exchange with H + or H 3O + ions from solution.2.Break-up of the silica network (Si-O-Si bonds) and the continued formation of Si-OH (silanols) at the glass solution interface.3.Condensation and repolymerisation of a SiO 2-rich layer on the surface, depleted in alkalis and alkali-earth cations.4.Migration of Ca+ and PO 4-3 groups to the surface forming a CaO-P 2O 5-rich film on top of the SiO 2-rich layer.5.Crystallization of the amorphous film byincorporation of OH- and CO 3-2 anions from solution to form solution to form a mixed hydroxyl carbonate apatite (HCA) layer.6.Adsorption and desorption of biological growth factors, in the HCA layer (continues throughout the process) to activate differentiation of stem cells.7. Action of macrophages to remove debris from the site allowing sells to occupy the space.8. Attachment of stem cells on the bioactive surface.9. Differentiation of stem cells to form bone growing cells, such as osteoblasts.10. Generation of extra cellular matrix by the osteoblasts to form bone.11. Crystallization of inorganic calcium phosphate matrix to enclose bone cells in a living composite structure.5It’s also established that the bioactive materials react chemically with the surrounding tissues and fluids.6CLINICAL APPLICATIONSIn vitro , extensive amount of studies have explored the behavior of bioactive glasses in different type ofsolutions. The amount of dissolution also depends on the particle size, type and powder form fraction.7 Others also indicated the effect of incorporating different elements such as Zinc to the alloys of Glass-ceramics for dental restorations.8 It was noticed that even though the amount of zinc was 1% of the dental alloy (high gold content), but it exhibited anomalous behavior because of the zinc incorporation in the oxide layer on the surface.8 Alsoother study concluded that sintering of the bioactive glass in 900C for 2 hours formed the most calcium phosphate layer after immersion in body simulated fluids.9 On the other hand, Roman et al.10 concluded that the additionSmile Dental Journal | Volume 7, Issue 2 - 2012 | 51|contain bone morphogenic proteins that are exposedwithin the bone matrix. Those BMP’s will in turn induce the pleuripotential stem cells to differentiate into osteoblasts and eventually to the production of new bone 25. Different human histological studies proved the formation of new attachment apparatus in the intrabony defects.25Others have used it to fill an extraction site to fill the defect and concluded completely filled sockets with mineralized tissue.26,27 Another study also confirmed the significant improvement when bioactive glass was used to fill extracted teeth sockets.28 Others have used the bioactive glass for sinus elevation procedures and found a significant formation of mineralized tissue in the chamber for future implant placement.29,30 Also, the bioactive glass was tried to treat bony defects around implants in dogs.31 In medical uses, the bioactive glass increased tissue strength when used to treat closed skin wounds in dogs.32CONCLUSIONOvertime, the need for materials to replace lost tissue was and still is a primary concern of dental researchers. Different materials have been developed and used. Some of the materials were not as safe and effective as they should have been in the past; that is why a new concept of bioactive materials based on glass-ceramics was developed. The bonding between the material and the tissues surrounding it has now proved its success clinically and these materials are used routinely in clinical settings on a daily basis.REFERENCES1. Ducheyne P . Bioceramics: material characteristics versus in vivobehavior. J Biomed Mater Res. 1987;21(A2 Suppl):219-36.2. Clark AE, Hench LL, Paschall HA. The influence of surface chemistryon implant interface histology: a theoretical basis for implant materials selection. J Biomed Mater Res. 1976;10(2):161-74.3. De Maeyer EA, Verbeeck RM. X-ray diffractometric determination ofcrystalline phase content in bioactive glasses. J Biomed Meter Res. 2001;57(3):467-72.4. De Diego MA, Coleman NJ, Hench LL. Tensile properties ofbioactive fibers for tissue engineering applications. J Biomed Mater Res. 2000;53(3):199-203.5. Jones JR, Sepulveda P , Hench LL. Dose-dependent behavior ofbioactive glass dissolution. J Biomed Mater Res. 2001;58(6):720-6.6. Ducheyne P , Cuckler JM. Bioactive ceramic prosthetic coatings. ClinOrthop. 1992;(276):102-14.7. Sepulveda P , Jones JR, Hench L. In vitro dissolution of melt-derived 45S5 and sol-gel derived 58S bioactive glass. Journal ofBiomedical materials research. 2002;301-11.8. Clare AG. Drescher H. Rheinberger V . Hoeland W . Glass scienceand technology-glastechnisc Berichite. 2000;73:278-85.9. Clupper DC, Mecholsky JJ Jr, LaTorre GP , Greenspan DC.Bioactivity of tape cast and sintered bioactive glass-ceramic in simulated body fluid. Biomaterials. 2002;23(12):2599-606.10. Roman J, Salinas AJ, Vallet-Regi M, Oliveira JM, Correia RN,Fernandes MH. Role of acid attack in the in vitro bioactivity of a glass-ceramic of the 3CaO.P2O5-CaO.SiO2-CaO.MgO.2SiO2 system. Biomaterials. 2001;22(14):2013-9.11. Serro AP , Fernandes AC, Saramago B, Fernandes MH. In vitromineralization of a glass-ceramic of the MgO-3CaO x P2O5-SiO2 system: wettability studies. J Biomed Mater Res. 2002;61(1):99-108.of hydroxyl apatite to the glass-ceramic will favor apatite formation in vitro . Serro et al.11 concluded that a calcium phosphate layer was formed at the surface of bioactive –glass ceramic (MgO-3CaO. P2O5-SiO 2) after one week of immersion in either simulated body fluids or Hank’s balanced salt solution. Others found such layer form as early as one hour of immersion in either serum containing solution or buffer solution supplemented with plasma.12 In addition to the calcium phosphate formation, excavation of the Bioactive Glass particle can also be observed in serum containing solutions.13In vivo , when any implanted material contact blood, blood coagulation or thrombus formation is the end result.14 Such behavior is not acceptable when designing materials intended to be implanted as prosthetic devices.14 The birth of bioactive glasses took another trend in which they can bond chemically to bone and induce its formation without inducing harmful effects during implantation.15 Since bone is continually remodeled by the actions of osteoblasts and osteoclats.16 Some studies looked at the effect of bioactive glass and osteoblasts. Xynos et al. observed the up regulation of osteoblasts gene expression when treated with Bioglass.17 Itala et al.18 concluded that cell attachment of osteoblasts increased and more surface reactivity occurred if the bioactive glass was micro roughened. Studies have also confirmed that the behavior of bioactive glasses in the body as osteoconductive (does not stimulatebone formation if bone forming sells are not present).19 Bioactive glass was also used to coat dental implants.20 Others suggested the use of bioactive glass as an antibiotic carrier.21Systemic antibiotics don’t always reach sufficientconcentrations for the bony tissues because of the poor blood flow to the areas. In return, higher doses are required to reach the therapeutic level to reach theaffected region. Currently, the local drug-delivery systems are an important topic in the medical and dental fields at this time.22 Meseguer-Olmo et al.23 concluded that the usage of bioactive glasses in an animal model as a carrier for gentamicin sustained a good concentration that was always above the minimum inhibitoryconcentration level throughout the 12 week study with the bony growth on the defect. Currently such studies will lead to the future introduction of commerciallyavailable bioactive glasses that can be used as carriers for antibiotics that can be used widely in the fields of medicine and dentistry.Bioactive glasses are used widely today in medical and dental applications. Bioactive glass is used in dental application as a bone substitute material inrestoring periodontal defects.24 When applied to restore periodontal defects, bioactive glass was comparable to the demineralized freezed dried bone (DFDBA) which is usually processed from cadavers.24 DFDBA particles| 52 |Smile Dental Journal | Volume 7, Issue 2 - 201212. Kaufmann EA, Ducheyne P , Radin S, Bonnell DA, CompostoR. Initial events at the bioactive glass surface in contact with protein-containing solutions. J Biomed Mater Res. 2000;52(4):825-30.13. Radin S, Ducheyne P , Falaize S, Hammond A. In vitrotransformation of bioactive glass granules into Ca-P shells. J Biomed Mater Res. 2000;49(2):264-72.14. Baier RE, Dutton RC. Initial events in interactions of blood witha foreign surface. J Biomed Mater Res. 1969;3(1):191-206.15. Ducheyne P, Cuckler JM. Bioactive ceramic prosthetic coatings. Clin Orthop. 1992;(276):102-14.16. Dziak R. Biochemical and molecular mediators of bonemetabolism. Journal of Periodontology. 1993;64(5):407-15.17. Xynos ID, Edgar AJ, Buttery LD, Hench LL, Polak JM. Gene-expression profiling of human osteoblasts following treatment with the ionic products of Bioglass 45S5 dissolution. J Biomed Mater Res. 2001;55(2):151-7.18. Itala A, Ylanen HO, Yrjans J, Heino T , Hentunen T , Hupa M,Aro HT . (2002) Characterization of microrough bioactive glass surface: surface reactions and osteoblast responses in vitro . J Biomed Mater Res. 2002;62(3):404-11.19. Ducheyne P . Bioceramics: material characteristics versus in vivobehavior. J Biomed Mater Res. 1987;21(A2 Suppl):219-36.20. Schrooten J, Van Oosterwyck H, Vander Sloten J, Helsen JA.(1999) Adhesion of new bioactive glass coating. J Biomed Mater Res. 1999;44(3):243-52.21. Griffon DJ, Dunlop DG, Howie CR, Gilchrist T , Salter DM, HealyDM. Early dissolution of a morsellised impacted silicate-free bioactive glass in metaphyseal defects. J Biomed Mater Res. 2001;58(6):638-44.22. Otsuka M, Matsuda Y , Kokubo T , Yoshihara S, NakamuraT ,Yamamuro T . Drug release from a novel self-settingbioactive glass bone cement containing cephalexin and its physicochemical properties. J Biomed Mater Res. 1995;29:33–8.23. L. Meseguer-Olmo, M. J. Ros-Nicolás, M. Clavel-Sainz, V .Vicente-Ortega, M. Alcaraz-Baños, A. Lax-Pérez, D. Arcos, C. V . Ragel, M. Vallet-Regí. Biocompatibility and in vivo gentamicin release from bioactive sol–gel glass implants. J Biomed Mater Res. 2002;61(3):458-65.24. Lovelace TB, Mellonig JT , Meffert RM, Jones AA, NummikoskiPV , Cochran DL. Clinical evaluation of bioactive glass in the treatment of periodontal osseous defects in humans. J Periodontol. 1998;69(9):1027-35.25. Alexandrina L. Dumitrescu. Chemicals in surgical periodontaltherapy: Bone grafts and bone graft substitutes in periodontal therapy. 2011; Edition IX. London, New York: Springer.26. Novaes J. Papalexiou V . Luczyszyn SM. Muglia VA. Souza SL.Taba JM. Immediate implant in extraction socket with acellular dermal matrix graft and bioactive glass: a case report. Implant Dentistry. 2002;11(4):343-8. 27. Sy IP . Alveolar ridge preservation using a bioactive glassparticulate graft in extraction site defects. Gen Dent. 2002;50(1):66-8.28. Throndson RR, Sexton SB. Grafting mandibular third molarextraction sites: a comparison of bioactive glass to anongrafted site. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94(4):413-9.29. Cordioli G. Mazzocco C. Schepers E. Majzoub Z. Maxillarysinus floor augmentation using bioactive glass and autogenous bone with simultaneous implant placement. Clinical Oral implants Reasearch. 2001;12(3):270-8,.30. Leonetti JA. Rambo HM. Throndson RR. Osteotome sinuselevation and implant placement with narrow size bioactive glass. Implant Dentistry. 2000;9(2):177-82,.31. Hall EE, Meffert RM, Hermann JS, Mellonig JT , CochranDL. Comparison of bioactive glass to demineralized freeze-dried bone allograft in the treatment of intrabony defects around implants in the canine mandible. J Periodontol. 1999;70(5):526-35.32. Gillette RL, Swaim SF , Sartin EA, Bradley DM, Coolman SL.Effects of a bioactive glass on healing of closed skin wounds in dogs. Am J Vet Res. 2001;62(7):1149-53.。
生物酶法制备壳寡糖的现状与未来
生物酶法制备壳寡糖的现状和展望壳寡糖(Chitosan oligosaccharide)，是以氨基葡萄糖为单体通过β-1,4-糖苷键连接的不同聚合度的混合物。
其水溶性好、功能作用大、生物活性高的低分子量产品，分子量小于3000Da。
随着对壳寡糖功能的深入研究，壳寡糖在农业、食品、日用化工、医药等各大领域有突出的效果。
农业上，壳寡糖的抑菌、抗病毒效果，可开发无公害生物农药，它的别称是氨基寡糖素。
另外，壳寡糖促进植物的营养生长，作为零污染的肥料；食品工业方面，壳寡糖具有提高免疫力，抗氧化，降三高的良好功能，是许多食品、保健品追捧的新食品原料；日用化工上，壳寡糖的吸水保湿功效，许多面膜、护肤品等都添加了壳寡糖；壳寡糖具有抗肿瘤、降血压等医疗功效，甚至可以作为疫苗的佐剂，为新药的开发提供思路和原料。
壳寡糖的功能决定着它的巨大市场需求，市场就推动了壳寡糖产业的发展。
目前壳寡糖工业化的生产主要是两种方法：一、物理化学法，通过机械粉碎虾蟹壳，用强碱去蛋白，无机酸脱盐制成壳聚糖，再用微波辐射或强酸降解壳聚糖生产壳寡糖；二、生物酶法，用生物酶降解壳聚糖生产壳寡糖。
物理化学法生产壳寡糖，高污染低质量受到了政府的制约和市场的淘汰，现市面上优质的壳寡糖产品绝大多数是生物酶法生产。
对于第二种方法生产壳寡糖有如下展望。
第一、发现并利用具有更优性质的生物酶目前，商业化的水解酶有溶菌酶、纤维素酶、木瓜蛋白酶、果胶酶、半纤维素酶对甲壳素和壳聚糖的水解有或多或少的催化效果 [1]. 这些非特异性酶连同特异性的甲壳素酶、壳聚糖酶、糖基转移酶等混合使用很可能开辟最优生物酶法制备壳寡糖的新道路。
虽然不同的非特异性酶有用来以壳聚糖或甲壳素为原料制备壳寡糖，但由于此类酶的水解能力有限，所以探寻更优特质水解酶是有市场需求的。
譬如，分支酶Branchzyme，可作用于壳聚糖并生成聚合度为2-20的壳寡糖，其中聚合度3-8的比例非常高[3]。
研究甲壳素或壳聚糖降解时中会发现，最初的步骤都是考虑将它们溶解，如果有能够直接降解结晶多糖的酶那就是省时高效的工业简化。
关于环境的英语高考作文
Environmental issues have become a focal point of global concern,and it is imperative that we take action to protect our planet.Here are some points that could be included in an essay on the environment,suitable for a high school English exam:1.Introduction to Environmental ProblemsBegin by introducing the severity of environmental issues such as climate change, deforestation,pollution,and loss of biodiversity.2.Causes of Environmental DegradationDiscuss the primary causes of environmental problems,including industrial activities, excessive use of fossil fuels,deforestation for agriculture,and the overconsumption of resources.3.Effects on Ecosystems and Human HealthExplain how environmental degradation affects ecosystems,leading to the extinction of species,and how it impacts human health through air and water pollution.4.Individual and Collective ResponsibilityEmphasize the role of individuals in making environmentally friendly choices,such as reducing waste,recycling,and conserving energy.Also,discuss the collective responsibility of governments and corporations to implement sustainable policies.5.Sustainable DevelopmentDefine sustainable development and its importance in balancing economic growth with environmental protection.Mention the United Nations Sustainable Development Goals SDGs as a global framework for action.6.Technological InnovationsHighlight the role of technology in addressing environmental challenges,such as renewable energy sources,electric vehicles,and energyefficient appliances.cation and AwarenessStress the importance of environmental education and raising public awareness about the consequences of environmental degradation and the steps that can be taken to mitigate it.8.International CooperationDiscuss the need for international cooperation in combating environmental issues, referencing global agreements like the Paris Agreement on climate change.9.Case StudiesProvide examples of successful environmental initiatives or policies from around the world that have had a positive impact on the environment.10.Conclusion and Call to ActionConclude the essay by reiterating the urgency of the situation and calling on readers to take action,whether through personal lifestyle changes or by supporting policies and initiatives that protect the environment.Remember to structure your essay with a clear introduction,body paragraphs that explore each point in detail,and a conclusion that summarizes the main ideas and leaves a lasting impression on the e a variety of sentence structures and vocabulary to demonstrate your language proficiency.。
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Degradation of some biorecalcitrant pesticides by homogeneous and heterogeneous photocatalytic ozonationMaria Jose´Farre ´a ,Maria Isabel Franch a ,Sixto Malato b ,Jose´Antonio Ayllo ´n a ,Jose ´Peral a ,Xavier Dome ´nech a,*aDepartament de Quı´mica,Universitat Auto ´noma de Barcelona,08193Bellaterra,Spain bQuı´mica Solar,Plataforma Solar de Almerı´a (CIEMAT),Crta de Senes,04200Tabernas (Almerı´a),Spain Received 2February 2004;received in revised form 8September 2004;accepted 13September 2004AbstractPhoto-Fenton/ozone (PhFO)and TiO 2-photocatalysis/ozone (PhCO)coupled systems are used as advanced oxida-tion processes for the degradation of the following biorecalcitrant pesticides:alachlor,atrazine,chlorfenvinfos,diuron,isoproturon and pentachlorophenol.These organic compounds are considered Priority Hazardous Substances by the Water Framework Directive of the European Commission.The degradation process of the different pesticides,that occurs through oxidation of the organic molecules by means of their reaction with generated OH radical,follows a first and zero-order kinetics,when PhFO and PhCO are applied,respectively.These two Advanced Oxidation Processes,together with the traditional ozone +UV,have been used to investigate TOC reduction of the different pesticide aque-ous solutions.The best results of pesticide mineralization are obtained when PhFO is applied;with the use of this advanced oxidation process the aqueous pesticide solutions become detoxyfied except in the case of atrazine and ala-chlor aqueous solutions for which no detoxification is achieved at the experimental conditions used in the work,at least after 2and 3h of treatment,respectively.Ó2004Published by Elsevier Ltd.Keywords:Photo-Fenton;TiO 2-photocatalysis;Ozone coupling;Pesticide degradation1.IntroductionThe presence of highly biorecalcitrant organic con-taminants in the hydrosphere due to industrial and intensive agricultural activities is of particular concern for the freshwater (surface and groundwater),coastal and marine environments.In view of this,it is advisableto develop technologies that promote the easy degrada-tion of these biorecalcitrant organic compounds.Apromising way to perform the mineralization of these type of substances is the application of advanced oxida-tion processes (AOP),that are characterized by the ‘‘in situ’’production of OH radicals under mild experimen-tal conditions (e.g.Peyton,1990).Among the different technologies proposed as AOP,are those based on the use of dissolved ozone (e.g.Glaze,1987;Peyton,1990).More recently,catalytic ozone based systems have been developed in order to enhance the OH radical production.In this way,it has been proposed the use of0045-6535/$-see front matter Ó2004Published by Elsevier Ltd.doi:10.1016/j.chemosphere.2004.09.064*Corresponding author.E-mail address:xavier.domenech@uab.es (X.Dome´nech).Chemosphere 58(2005)1127–1133/locate/chemospheresome metals in homogeneous solution(Fe(II),Mn(II), Ni(II)or Co(II))to induce an increase of total organic carbon(TOC)removal compared to ozonation alone (e.g.Legube and Karpel,1999),or the use of metal oxi-des for the enhancement of the ozonation in heteroge-neous processes(e.g.Legube and Karpel,1999). Another alternative to increase the OH radical produc-tion is the photocatalytic ozonation(both homogeneous and heterogeneous)by using Photo-Fenton(e.g.Log-ager et al.,1992;Piera et al.,2000)or TiO2-photocata-lysis(e.g.Sa´nchez et al.,1998;Piera et al.,2000;Beltra´n et al.,2002).In the present paper,both homogeneous and hetero-geneous photocatalytic ozonation are applied to assess the suitability of these AOP to promote mineralization of organic biorecalcitrant compounds.Concretely,water soluble pesticides included in Decision No.2455/2001/ EC of the European Parliament and of the Council of 20November2001,in which a list of priority substances in thefield of water policy is established,i.e.alachlor, atrazine,chorofenvinfos,diuron,isoproturon and pen-tachorophenol(PCP)have been chosen as target com-pounds.These organic pesticides,which exhibit a high degree of biotoxicity,have a moderate solubility in water(between15mgdmÀ3for pentachlorophenol to 240mgdmÀ3for alachlor at25°C)and low to moderate octanol–water constants,with log K OW around2.7–2.9, except for pentachlorophenol(log K OW=5.1)and chlo-rofenvinfos(log K OW=3.8).2.Experimental2.1.ReagentsAlachlor(95%,Aragonesas Agro SA technical grade),Atrazine(95%,Ciba-Geigy technical grade), Chlorfenvinphos(93.2%,Aragonesas Agro SA technical grade),Diuron(98.5%,Aragonesas Agro SA technical grade)and Isoproturon(98%,Aragonesas Agro SA technical grade)were used as target compounds in the experiments.PCP(98%)was purchased from Aldrich. All the aqueous solutions were prepared with water purified in a Millipore Milli-Q system.FeSO4Æ7H2O (Merck,99.5%)and H2O2(Panreac,33%p/v)were used in the Photo-Fenton experiments.TiO2P-25(80%ana-tase–20%rutile,59.1m2gÀ1,non-porous)was supplied by Degussa.KI(Panreac,analytical grade),KIO3(Pro-bus,analytical grade),K2H2PO4(Aldrich,analytical grade)and Na2S2O3Æ5H2O(Aldrich,analytical grade) were used for the iodometric titrations.Acetonitrile (Probus,HPLC grade)was used to prepare the mobile phases in the HPLC system.All the other chemicals mentioned hereafter were at least of reagent grade and used as received.2.2.Apparatus and analytical methodsThe pesticide degradation experiments were carried out in a Pyrex glass cell provided of a thermostatic jacket (25.0±0.1°C)and under magnetic stirring.Ozone,gen-erated by an Erwin Sander301.7equipment fed with pure oxygen(99.995%C-45,Carburos Meta´licosflow at P=1bar),was bubbled into the bottom of the reactor by means of a diffuser.The ozone input in the treated solution was 1.6ghÀ1as determined by iodometric titration(Method001/95International Ozone Associa-tion-EAG).The unreacted ozone in theflow gas was measured by means of an Erwin Sander Quantozone-1 ozone-meter.A6W black light(Philips)lamp was used as UVA source in the irradiation experiments.The concentration of the pesticides was measured by HPLC technique.The HPLC system was constituted by a LC-10AT VP pump(Shimadzu)and a UV–Visible diode array detector(Agilent1100Series).The station-ary phase was a Hypersil ODS Teknokroma column (250·4.6mm).An acetonitrile/water mixture(50/50 but60/40for alachlor)was employed as the mobile phase,except for PCP analysis for which a methanol/ water mixture(80/20)as the mobile phase was used. The mobile phase was degassed by sonication andfil-tered(0.45l m)before using.TOC determination was carried out with a TOC-5000Shimadzu Total Carbon Analyser.The toxicity tests were performed by means of a BioTox equipment(Lab-system)using the Vibrio fischery luminescence inhibition to assess the EC50val-ues.Before TOC and HPLC analysis,all the samples werefiltered trough0.45l m pore size nylonfilters in order to remove any particulates.It must be noted that no pesticide adsorption occurs on these type offilters.2.3.Pesticide degradation experimentsThe experiments were performed with200ml of an approximately50mglÀ1aqueous solution of the studied pesticide except for Atrazine and Diuron.For the latter products saturated solutions were prepared andfiltrated before being used.All experiments were performed at an initial pH of3.0,except for PCP for which the initial pH was7.0.HCl and NaOH diluted aqueous solutions were used to adjust the initial pH values.Although ClÀions in the aqueous medium can react withÆOH radicals ina process with a relatively high rate constant(4.3Æ109molÀ1l sÀ1)(Buston et al.,1988),recently it has been observed that theÆOH scavenging properties of ClÀion are only relevant at high concentrations (higher than0.1M(Kiwi et al.,2000).The reactor was filled with the pesticide solution once the ozone dosage input in the reactor was constant.In the Photo-Fen-ton/ozone and TiO2-photocatalysis/ozone systems,the Fenton reagent(5.0ml of a FeSO4Æ7H2O(80.0mglÀ1) aqueous solution and the suitable volume of H2O2)or1128M.J.Farre´et al./Chemosphere58(2005)1127–1133TiO2powders(0.0500g)were also added to the reactor cell.The quantity of H2O2employed was twice the stoichiometric amount necessary for the complete min-eralization of the studied pesticide.Concretely,the con-centrations of H2O2used in the Photo-Fenton and Photo-Fenton/ozone systems were the following: 0.48glÀ1,0.38glÀ1,0.26glÀ1,0.32glÀ1,0.61glÀ1and 0.11glÀ1for alachlor,atrazine,chlorfenvinfos,diuron, isoproturon and PCP,respectively.The excess of H2O2 used in this work is not enough to affect the efficiency of pesticide degradation due to OH radical consumption by H2O2.This only occurs when a very high H2O2con-centration is used(Pe´rez et al.,2002).Samples were periodically taken along time from the reactor to measure the pesticide concentration,TOC, and toxicity values.For the Photo-Fenton and TiO2-photocatalysis experiments the same procedure as PhFO and PhCO was followed but without ozone supply.In the experimental conditions of the degradation assays, the pesticides adsorption over the TiO2powders in the dark does not significantly contribute to their elimina-tion from the aqueous solution.3.Results and discussionThe coupling between ozone and Photo-Fenton (Fe(II),H2O2and UV)and heterogeneous(TiO2and UV)photocatalysis,was applied to the elimination of the following pesticides in aqueous solutions:alachlor, atrazine,chlorfenvinfos,diuron,isoproturon and PCP. All experiments were performed at initial pH of3.0,ex-cept for PCP degradation for which the initial pH was 7.0to increase the solubility of this pesticide in water. Along the photodegradation process the pH of the dif-ferent pesticides solutions remains almost constant,ex-cept in the case of PCP solutions in which a decrease of pH is observed during thefirst minutes of irradiation attaining a limiting value of about3,due to the acidity generated from the mineralization process.Fig.1shows the time course of the concentrations of the different pesticides investigated when Photo-Fenton/ ozone(PhFO)and TiO2-photocatalysis/ozone(PhCO) systems are applied to the aqueous pesticide solutions. From data depicted in Fig.1,the kinetics of degradation of the different studied pesticides has been deduced and the corresponding kinetic rate constants obtained are summarized in Table1.With relation to PhFO system,afirst-order kinetics for the degradation of all pesticides is deduced.For PCP,the decrease of pesticide concentration is very strong,resulting in a98%elimination after only30s, that precludes to perform a suitable kinetic analysis.In fact,in this case the experiments were performed at neu-tral pH at which O3is able,in comparison to pH3,to increase OH radical concentration trough a series of chemical and photochemical processes(see latter in the text).It can be assumed that the degradation of the pes-ticides occurs by direct OH attack to the organic mole-cule.The OH radical is produced by the Fenton reaction that occurs at acid pH(process(1))(e.g.Faust and Hoigne´,1990):Fe2þ+H2O2!Fe(OH)2þ+ÅOHð1ÞTable1First and zero order rate constants,k PhFO and k PhCO,respec-tively,of photocatalytic ozonation(PhFO and PhCO),of the different investigated pesticide in aqueous solutions at initial pH=3.0and at25°CPesticide k PhFOÆ103/sÀ1k PhCO·107/mollÀ1sÀ1 Alachlor 2.2 1.5Atrazine 4.0 3.3Chlorfenvinfos 4.211Diuron 6.27.8Isoproturon 6.2 6.0PCP a–29See Section2for experimental details.a Initial pH=7.0.M.J.Farre´et al./Chemosphere58(2005)1127–11331129Under irradiation of k<400nm Fe(III)can be reduced to Fe(II)closing a loop mechanism where Fe species act as catalyst,giving rise to additionalÅOH(e.g.Faust and Hoigne´,1990):Fe(OH)2þ+h m!Fe2þ+ÅOHð2ÞA further increment in the OH radicals production oc-curs when ozone is added to the solution;in this case, dissolved O3reacts with Fe2+giving rise to FeO2+that further undergoes hydrolysis to give Fe3+producing moreÅOH(e.g.Logager et al.,1992):Fe2þ+O3!FeO2þ+O2ð3ÞFeO2þ+H2O!Fe3þ+ÅOH+OHÀð4ÞDue to the catalytic role of Fe,the constant supply of ozone and photons to the reactive system and the excess of H2O2,the concentration ofÅOH produced remains constant and consequently the rate of pesticide degrada-tion depends only on its concentration according to a first order kinetics.With respect to the PhCO system,the reaction also proceed by radical attack to the organic molecule.The OH radical is produced by(i)reaction of adsorbed H2O molecules with photogenerated holes at the illumi-nated TiO2particle(process(6))and(ii)by reaction of adsorbed O3and photogenerated electrons at the TiO2 particle(processes(7)and(8))(e.g.Sa´nchez et al.,1998): TiO2+h m!eÀ+hþð5ÞH2O+hþ!ÅOH+Hþð6ÞO3þeÀ!OÀÅ3ð7ÞOÀÅ3þHþ!OHÅþO2ð8ÞThe presence of dissolved ozone in the irradiated TiO2aqueous suspension increases the OH radical pro-duction and decreases the electron–hole recombination, increasing the efficiency of the photocatalytic process. The observed zero-order kinetics,that has also been ob-served for other PhCO degradation processes(e.g.Bel-tra´n et al.,2002;Herna´ndez-Alonso et al.,2002),can be an indication that the rate determining step is the pro-duction of radical OH at the semiconductor surface.As can be seen,a similar rate constant of degradation of the studied pesticides by PhFO is obtained,except for alachlor that has the lowest rate constant;for PCPa high initial rate of elimination is estimated(1.5mg lÀ1sÀ1).With relation to PhCO system,alachlor and PCP are also the pesticides that show lower and higher rate constants of degradation respect to the other pesticides.The mineralization process of the studied pesticides by means of the application of different treatment proce-dures has been investigated.These treatment procedures are:heterogeneous TiO2-photocatalysis,Photo-Fenton, ozone+UV,PhCO and PhFO.At the experimental conditions used in this work and after at least120min of treatment,no TOC reduction has been observed when TiO2-photocatalysis and Photo-Fenton are applied at atrazine,diuron,isoproturon and PCP aqueous solu-tions and also when ozone+UV and Photo-Fenton are used for treating atrazine and alachlor solutions, respectively.TiO2-photocatalysis shows a low activity respect to TOC reduction for alachlor and chlorfenvin-fos aqueous systems,attaining in both cases a limiting TOC reduction of24%and25%at180and60min of treatment,respectively.On the other hand,chlorofen-vinfos is rather stable when Photo-Fenton process is ap-plied at the studied experimental conditions,achieving a limiting TOC reduction of only20%after75min of treatment.In Figs.2–4,the variation of the ratio TOC/TOC0as a function of irradiation time for the different pesticide aqueous systems treated by means of PhFO,PhCO and ozone+UV processes is represented.As can be seen,atrazine is the studied pesticide more resistant to mineralization by these three treatment systems,i.e., after90min of treatment only30%and10%of the initial TOC is reduced,when PhFO and PhCO systems are used,respectively,while no noticeable degradation oc-curs when ozone+UV is applied.The best results con-cerning to TOC reduction are obtained by the application of PhFO system for all pesticides solutions investigated.PhCO gives better results than ozone+UV for the degradation of all pesticides except for PCP.It has to be remembered that for PCP all the experiments have been performed at an initial neutral pH.This is particularly relevant when using ozone+UV system, for which besides the direct attack of ozone tothe1130M.J.Farre´et al./Chemosphere58(2005)1127–1133organic molecule,at neutral to alkaline environments the indirect process of degradation trough OH radical reaction becomes relevant.At this pH,the OH radicals are generated by means of reaction between O 3andOH Àions (e.g.,Staehelin and Hoigne ´,1982):O 3þOH À!O ÀÅ2þHO Å2ð9ÞO ÀÅ2þO 3!O 2þO ÀÅ3ð10ÞO ÀÅ3þH þ!HO Å3!ÅOH þO 2ð11ÞThe production of OH radical is increased under UVillumination through the formation of H 2O 2(process (12)),which after acid–base dissociation and reactionwith O 3give rise to the formation of O À3Å(processes (13)and (14))(e.g.Peyton,1990):O 3þH 2O þh m !H 2O 2þO 2ð12ÞH 2O 2 HO À2þH þð13ÞO 3þHO À2!O ÀÅ3þHO Å2ð14ÞThe O À3Åradicals generated in the last step produce OHradicals through reaction (11).The initial rates of pesticide mineralization through the application of PhFO,PhCO and ozone +UV sys-tems obtained from the slopes of the TOC/TOC 0vs.t curves up to the first 15min (Figs.2–4)are summarized in Table 2.From that data the order of degradability of the different pesticides through the application of PhFO and ozone +UV systems is:PCP >chlorfenvinfos >diuron >isoproturon>alachlor >atrazineOn the other hand,when the PhCO system is applied,the initial rate of mineralization of all pesticides investi-gated varies in a very narrow range (between 7and 12gl À1s À1),except for atrazine for which an initial rate value of an order of magnitude lower is observed (see Table 2).Further,it is interesting to note that after,approximately,the first 15min of irradiation,the rate of mineralization of all pesticides are very similar (about 0.5%TOC reduction per min),except for atrazine which TOC reduction rate is much lower (about 0.1%TOC per min).As it has been said previously,atrazine is the most re-calcitrant pesticide studied in this work,i.e.,very low TOC reduction values are achieved when PhFO and PhCO systems are applied (i.e.,34%and 15%TOC reduction after 100min of irradiation,respectively),Table 2Initial rate of pesticide mineralization in mgl À1s À1through the application of PhFO (r PhFO ),PhCO (r PhCO )and ozone +UV (r ozone )AOPs at initial pH =3.0and at 25°C Pesticide r PhFO Æ103r PhCO Æ103r ozone Æ103Alachlor 8.312 3.8Atrazine2.20.80.4Chlorfenvinfos 221416Diuron157.87.2Isoproturon 147.3 4.7PCP a351223See Section 2for experimental details.aInitial pH =7.0.M.J.Farre´et al./Chemosphere 58(2005)1127–11331131while no TOC reduction is observed when ozone+UV is used.In fact,it is well known the formation of cyan-uric acid during degradation of atrazine,a compound that is very stable to OH radical attack(e.g.,Pelizzetti et al.,1992;Huston and Pignatello,1999).Also,in the case of diuron and PCP,although they are strongly de-graded by means of PhFO application,a limiting value of TOC reduction of70%and90%at60min of irradia-tion,respectively,is attained indicating the formation of recalcitrant intermediates at the last steps of degradation (Malato et al.,2003).The toxicity of the pesticide solutions treated by means of PhFO system,which is the AOP that gives the best results concerning pesticide degradation,has been assessed.The EC50-values obtained for the different pesticide initial aqueous solutions were:70.8,55.2,153.9, 49.2,28.0and0.25for alachlor(TOC0=31.1mglÀ1), diuron(TOC0=17.3mglÀ1),atrazine(TOC0=15.8 mglÀ1),chlorofenvinfos(TOC0=21.2mglÀ1),and iso-proturon(TOC0=32.7mglÀ1)and PCP(TOC0= 12.9mglÀ1),respectively.In Fig.5,the1/EC50TOC val-ues for pesticides solutions,except for PCP,are repre-sented as a function of treatment time.It is observed that in all cases,except for alachlor,an increase of toxi-city occurs achieving a maximum value at a treatment time that depends on the pesticide nature.An increase of toxicity has also been reported in the photocatalytic degradation of isoproturon and diuron,a fact that has been ascribed to the formation of more toxic intermedi-ates than the parent compound(Parra et al.,2002; Malato et al.,2003).For diuron,isoproturon and chlor-fenvinfos,their solutions become detoxified after passing the maximum toxicity and at treatment times no longer than100min at the reported experimental conditions. It must be signaled that for these three pesticides,detox-ification is attained when the TOC remaining in solution becomes lower than10mglÀ1.On the other hand,PhFO system is not able to detox-ify atrazine and alachlor solutions at least at treatment times lower than2and3h,respectively.For alachlor the toxicity of their aqueous solutions increases with increasing treatment time,at least after3h of irradiation (see Fig.5).Other authors have reported the formation of2,6-diethylaniline as degradation product of alachlor, being responsible of the observed increased toxicity of treated alachlor aqueous solutions(Osano et al.,2002). In the case of PCP aqueous solution,for which the ini-tial1/E ECÆTOC value is0.31,30min of treatment is en-ough to produce a detoxified solution,particularly due to the strong TOC reduction that occurs when PhCO is applied(see Fig.2).4.ConclusionsThe PhFO and PhCO advanced oxidation processes lead to a rapid decrease of the concentration of the biorecalcitrant pesticides,alachlor,atrazine,chlorfen-vinfos,diuron and PCP in aqueous solutions.The degra-dation processes,that occur through oxidation of the organic molecules by means of their reaction with gener-ated OH radical,follow afirst and zero-order kinetics, when PhFO and PhCO are applied respectively.The application of PhFO,PhCO and ozone+UV systems to the pesticide aqueous solutions leads to a strong TOC reduction,except for atrazine for which no TOC reduction is observed with the ozone+UV treament and very low values of TOC decrease are observed when PhFO and PhCO systems are used.The best results of pesticide degradation are obtained when PhFO is ap-plied.The pesticide solutions,after being treated by means of PhFO system,become detoxyfied except for atrazine and alachlor aqueous solutions for which no detoxification is achieved at least after2and3h of treat-ment,respectively.In the case of alachlor the toxicity of the treated solutions increases with increasing irradia-tion time,at least after3h of irradiation. 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